diff --git a/.eslintignore b/.eslintignore
index da5b7db6d088..66e77b32f840 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -101,7 +101,6 @@ browser/extensions/formautofill/phonenumberutils/PhoneNumberMetaData.jsm
 # devtools/ exclusions
 devtools/client/inspector/markup/test/doc_markup_events_*.html
 devtools/client/inspector/rules/test/doc_media_queries.html
-devtools/client/memory/test/chrome/*.html
 devtools/client/performance/components/test/test_jit_optimizations_01.html
 devtools/client/responsive.html/test/browser/touch.html
 devtools/client/shared/components/test/mochitest/*.html
diff --git a/devtools/client/memory/test/chrome/test_CensusTreeItem_01.html b/devtools/client/memory/test/chrome/test_CensusTreeItem_01.html
index 418dbc36b204..f940fbe68ae9 100644
--- a/devtools/client/memory/test/chrome/test_CensusTreeItem_01.html
+++ b/devtools/client/memory/test/chrome/test_CensusTreeItem_01.html
@@ -16,7 +16,8 @@ Test that children pointers show up at the correct times.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              const container = document.getElementById("container");
 
@@ -52,8 +53,7 @@ Test that children pointers show up at the correct times.
 
              ok(container.querySelector(".children-pointer"),
                 "Do show children pointer when non-inverted and have children");
-
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_DominatorTreeItem_01.html b/devtools/client/memory/test/chrome/test_DominatorTreeItem_01.html
index 6937e1fc3115..070a1154f07f 100644
--- a/devtools/client/memory/test/chrome/test_DominatorTreeItem_01.html
+++ b/devtools/client/memory/test/chrome/test_DominatorTreeItem_01.html
@@ -16,7 +16,8 @@ Test that we don't display `JS::ubi::RootList` for the root, and instead show "G
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              const container = document.getElementById("container");
 
@@ -33,7 +34,7 @@ Test that we don't display `JS::ubi::RootList` for the root, and instead show "G
                 "Should not display `JS::ubi::RootList`");
              ok(container.textContent.includes("GC Roots"),
                 "Should display `GC Roots` instead");
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_DominatorTree_01.html b/devtools/client/memory/test/chrome/test_DominatorTree_01.html
index 518d3504c841..45cd7dfe2271 100644
--- a/devtools/client/memory/test/chrome/test_DominatorTree_01.html
+++ b/devtools/client/memory/test/chrome/test_DominatorTree_01.html
@@ -16,7 +16,8 @@ Test that we show a place holder for a subtree we are lazily fetching.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              const container = document.getElementById("container");
 
@@ -26,19 +27,20 @@ Test that we show a place holder for a subtree we are lazily fetching.
              const expanded = new Set();
              expanded.add(root.nodeId);
 
-             await renderComponent(DominatorTreeComponent(immutableUpdate(TEST_DOMINATOR_TREE_PROPS, {
-               dominatorTree: immutableUpdate(TEST_DOMINATOR_TREE_PROPS.dominatorTree, {
-                 expanded,
-                 root,
-                 state: dominatorTreeState.INCREMENTAL_FETCHING,
-                 activeFetchRequestCount: 1,
-               }),
-             })), container);
+             await renderComponent(DominatorTreeComponent(immutableUpdate(
+                TEST_DOMINATOR_TREE_PROPS, {
+                   dominatorTree: immutableUpdate(TEST_DOMINATOR_TREE_PROPS.dominatorTree, {
+                     expanded,
+                     root,
+                     state: dominatorTreeState.INCREMENTAL_FETCHING,
+                     activeFetchRequestCount: 1,
+                   }),
+                })), container);
 
              ok(container.querySelector(".subtree-fetching"),
                 "Expanded nodes with more children available, but no children " +
                 "loaded, should get a placeholder");
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_DominatorTree_02.html b/devtools/client/memory/test/chrome/test_DominatorTree_02.html
index ae8e80b1dcc3..74662fe0708d 100644
--- a/devtools/client/memory/test/chrome/test_DominatorTree_02.html
+++ b/devtools/client/memory/test/chrome/test_DominatorTree_02.html
@@ -16,7 +16,8 @@ Test that we show a link to load more children when some (but not all) are loade
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              const container = document.getElementById("container");
 
@@ -29,16 +30,17 @@ Test that we show a link to load more children when some (but not all) are loade
              const expanded = new Set();
              expanded.add(root.nodeId);
 
-             await renderComponent(DominatorTreeComponent(immutableUpdate(TEST_DOMINATOR_TREE_PROPS, {
-               dominatorTree: immutableUpdate(TEST_DOMINATOR_TREE_PROPS.dominatorTree, {
-                 expanded,
-                 root,
-               }),
-             })), container);
+             await renderComponent(DominatorTreeComponent(immutableUpdate(
+                TEST_DOMINATOR_TREE_PROPS, {
+                   dominatorTree: immutableUpdate(TEST_DOMINATOR_TREE_PROPS.dominatorTree, {
+                     expanded,
+                     root,
+                   }),
+                })), container);
 
              ok(container.querySelector(".more-children"),
                 "Should get a link to load more children");
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_DominatorTree_03.html b/devtools/client/memory/test/chrome/test_DominatorTree_03.html
index 2f75ed711daa..10280f15f8d3 100644
--- a/devtools/client/memory/test/chrome/test_DominatorTree_03.html
+++ b/devtools/client/memory/test/chrome/test_DominatorTree_03.html
@@ -16,7 +16,8 @@ Test that expanded DominatorTreeItems are correctly rendered and updated
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-        window.onload = async function () {
+        "use strict";
+        window.onload = async function() {
           try {
             const container = document.getElementById("container");
 
@@ -32,7 +33,7 @@ Test that expanded DominatorTreeItems are correctly rendered and updated
             const expanded = new Set();
             expanded.add(root.nodeId);
 
-            let component = await renderComponent(
+            await renderComponent(
               DominatorTreeComponent(immutableUpdate(
                 TEST_DOMINATOR_TREE_PROPS,
                 {
@@ -64,8 +65,7 @@ Test that expanded DominatorTreeItems are correctly rendered and updated
                 "Should display only one row");
             is(container.querySelectorAll(".arrow.open").length, 0,
                 "Should display no expanded arrow");
-
-          } catch(e) {
+          } catch (e) {
             ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
           } finally {
             SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_Heap_01.html b/devtools/client/memory/test/chrome/test_Heap_01.html
index ebd9076ea805..983eef40d205 100644
--- a/devtools/client/memory/test/chrome/test_Heap_01.html
+++ b/devtools/client/memory/test/chrome/test_Heap_01.html
@@ -15,7 +15,8 @@ Test that rendering a dominator tree error is handled correctly.
         <script src="head.js" type="application/javascript"></script>
 
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              ok(React, "Should get React");
              ok(Heap, "Should get Heap");
@@ -38,7 +39,7 @@ Test that rendering a dominator tree error is handled correctly.
              ok(container.querySelector(".error"), "Should render an error view");
              ok(container.textContent.includes(errorMessage),
                 "Should see our error message");
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_Heap_02.html b/devtools/client/memory/test/chrome/test_Heap_02.html
index 630f7972d4e9..e4c5281893e8 100644
--- a/devtools/client/memory/test/chrome/test_Heap_02.html
+++ b/devtools/client/memory/test/chrome/test_Heap_02.html
@@ -14,12 +14,12 @@ Test that the currently selected view is rendered.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              ok(React, "Should get React");
              ok(Heap, "Should get Heap");
 
-             const errorMessage = "Something went wrong!";
              const container = document.getElementById("container");
 
              // Dominator tree view.
@@ -66,7 +66,7 @@ Test that the currently selected view is rendered.
 
              ok(container.querySelector("[data-state=initial]"),
                 "With no snapshot, nor a diffing, should render initial prompt.");
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_Heap_03.html b/devtools/client/memory/test/chrome/test_Heap_03.html
index d33a30e7e531..bd6fa26e962e 100644
--- a/devtools/client/memory/test/chrome/test_Heap_03.html
+++ b/devtools/client/memory/test/chrome/test_Heap_03.html
@@ -15,11 +15,12 @@ but not in other dominator tree states.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              const container = document.getElementById("container");
 
-             for (let state of [dominatorTreeState.COMPUTING, dominatorTreeState.FETCHING]) {
+             for (const state of [dominatorTreeState.COMPUTING, dominatorTreeState.FETCHING]) {
                await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                  view: { state: viewState.DOMINATOR_TREE, },
                  snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
@@ -35,13 +36,17 @@ but not in other dominator tree states.
                   `Should show a throbber for state = ${state}`);
              }
 
-             for (let state of [dominatorTreeState.LOADED, dominatorTreeState.INCREMENTAL_FETCHING]) {
+             for (
+              const state of [
+               dominatorTreeState.LOADED, dominatorTreeState.INCREMENTAL_FETCHING
+              ]) {
                await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                  view: { state: viewState.DOMINATOR_TREE, },
                  snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
                    dominatorTree: immutableUpdate(TEST_HEAP_PROPS.snapshot.dominatorTree, {
                      state,
-                     activeFetchRequestCount: state === dominatorTreeState.INCREMENTAL_FETCHING ? 1 : undefined,
+                     activeFetchRequestCount:
+                      state === dominatorTreeState.INCREMENTAL_FETCHING ? 1 : undefined,
                    }),
                  }),
                })), container);
@@ -62,7 +67,7 @@ but not in other dominator tree states.
 
              ok(!container.querySelector(".devtools-throbber"),
                 `Should not show a throbber for ERROR state`);
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_Heap_04.html b/devtools/client/memory/test/chrome/test_Heap_04.html
index c80c0a6104a6..0752009c8bfa 100644
--- a/devtools/client/memory/test/chrome/test_Heap_04.html
+++ b/devtools/client/memory/test/chrome/test_Heap_04.html
@@ -14,7 +14,8 @@ Test that we show the "hey you're not recording allocation stacks" message at th
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              const container = document.getElementById("container");
 
@@ -109,7 +110,7 @@ Test that we show the "hey you're not recording allocation stacks" message at th
 
              ok(!container.querySelector(".no-allocation-stacks"),
                 "When there isn't census data, we should not show the message");
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_Heap_05.html b/devtools/client/memory/test/chrome/test_Heap_05.html
index 4662e09e89f7..005662ac39eb 100644
--- a/devtools/client/memory/test/chrome/test_Heap_05.html
+++ b/devtools/client/memory/test/chrome/test_Heap_05.html
@@ -14,7 +14,8 @@ Test that we show a message when the census results are empty.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              const container = document.getElementById("container");
 
@@ -110,17 +111,17 @@ Test that we show a message when the census results are empty.
 
              await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
-                 census: immutableUpdate(TEST_HEAP_PROPS.snapshot.census, immutableUpdate(emptyCensus, {
-                   filter: "zzzz"
-                 })),
+                 census: immutableUpdate(
+                   TEST_HEAP_PROPS.snapshot.census, immutableUpdate(emptyCensus, {
+                    filter: "zzzz"
+                   })),
                }),
              })), container);
 
              ok(container.querySelector(".empty"),
                 "When the report is empty in census view w/ filter, we show the empty message");
              ok(container.textContent.includes(L10N.getStr("heapview.none-match")));
-
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_List_01.html b/devtools/client/memory/test/chrome/test_List_01.html
index a3fd2f70a99f..21b7c1a33f57 100644
--- a/devtools/client/memory/test/chrome/test_List_01.html
+++ b/devtools/client/memory/test/chrome/test_List_01.html
@@ -15,59 +15,58 @@ Test to verify the delete button calls the onDelete handler for an item
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
-          try {
-            const container = document.getElementById("container");
+          "use strict";
+          window.onload = async function() {
+            try {
+              const container = document.getElementById("container");
 
-            let deletedSnapshots = [];
+              const deletedSnapshots = [];
 
-            let snapshots = [ TEST_SNAPSHOT, TEST_SNAPSHOT, TEST_SNAPSHOT ]
-              .map((snapshot, index) => immutableUpdate(snapshot, {
-                index: snapshot.index + index
-              }));
+              const snapshots = [ TEST_SNAPSHOT, TEST_SNAPSHOT, TEST_SNAPSHOT ]
+                .map((snapshot, index) => immutableUpdate(snapshot, {
+                  index: snapshot.index + index
+                }));
 
-            await renderComponent(
-              List({
-                itemComponent: SnapshotListItem,
-                onClick: noop,
-                onDelete: (item) => deletedSnapshots.push(item),
-                items: snapshots
-              }),
-              container
-            );
+              await renderComponent(
+                List({
+                  itemComponent: SnapshotListItem,
+                  onClick: noop,
+                  onDelete: (item) => deletedSnapshots.push(item),
+                  items: snapshots
+                }),
+                container
+              );
 
-            let deleteButtons = container.querySelectorAll('.delete');
+              const deleteButtons = container.querySelectorAll(".delete");
 
-            is(container.querySelectorAll('.snapshot-list-item').length, 3,
-              "There are 3 list items\n");
-            is(deletedSnapshots.length, 0,
-              "Not snapshots have been deleted\n");
+              is(container.querySelectorAll(".snapshot-list-item").length, 3,
+                "There are 3 list items\n");
+              is(deletedSnapshots.length, 0,
+                "Not snapshots have been deleted\n");
 
-            deleteButtons[1].click();
+              deleteButtons[1].click();
 
-            is(deletedSnapshots.length, 1, "One snapshot was deleted\n");
-            is(deletedSnapshots[0], snapshots[1],
-              "Deleted snapshot was added to the deleted list\n");
+              is(deletedSnapshots.length, 1, "One snapshot was deleted\n");
+              is(deletedSnapshots[0], snapshots[1],
+                "Deleted snapshot was added to the deleted list\n");
 
-            deleteButtons[0].click();
+              deleteButtons[0].click();
 
-            is(deletedSnapshots.length, 2, "Two snapshots were deleted\n");
-            is(deletedSnapshots[1], snapshots[0],
-              "Deleted snapshot was added to the deleted list\n");
+              is(deletedSnapshots.length, 2, "Two snapshots were deleted\n");
+              is(deletedSnapshots[1], snapshots[0],
+                "Deleted snapshot was added to the deleted list\n");
 
-            deleteButtons[2].click();
+              deleteButtons[2].click();
 
-            is(deletedSnapshots.length, 3, "Three snapshots were deleted\n");
-            is(deletedSnapshots[2], snapshots[2],
-              "Deleted snapshot was added to the deleted list\n");
-
-
-          } catch(e) {
-            ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
-          } finally {
-            SimpleTest.finish();
-          }
-         };
+              is(deletedSnapshots.length, 3, "Three snapshots were deleted\n");
+              is(deletedSnapshots[2], snapshots[2],
+                "Deleted snapshot was added to the deleted list\n");
+            } catch (e) {
+              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
+            } finally {
+              SimpleTest.finish();
+            }
+          };
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_ShortestPaths_01.html b/devtools/client/memory/test/chrome/test_ShortestPaths_01.html
index b0bace20c4b0..79f39f30b916 100644
--- a/devtools/client/memory/test/chrome/test_ShortestPaths_01.html
+++ b/devtools/client/memory/test/chrome/test_ShortestPaths_01.html
@@ -23,7 +23,8 @@ Test that the ShortestPaths component properly renders a graph of the merged sho
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              const container = document.getElementById("container");
 
@@ -38,7 +39,7 @@ Test that the ShortestPaths component properly renders a graph of the merged sho
              let found2to3 = false;
 
              const tspans = [...container.querySelectorAll("tspan")];
-             for (let el of tspans) {
+             for (const el of tspans) {
                const text = el.textContent.trim();
                dumpn("tspan's text = " + text);
 
@@ -99,8 +100,7 @@ Test that the ShortestPaths component properly renders a graph of the merged sho
              ok(found1to2, "Should have rendered edge 1->2");
              ok(found1to3, "Should have rendered edge 1->3");
              ok(found2to3, "Should have rendered edge 2->3");
-
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_ShortestPaths_02.html b/devtools/client/memory/test/chrome/test_ShortestPaths_02.html
index 5b48bd49f6a6..a63547467917 100644
--- a/devtools/client/memory/test/chrome/test_ShortestPaths_02.html
+++ b/devtools/client/memory/test/chrome/test_ShortestPaths_02.html
@@ -23,7 +23,8 @@ Test that the ShortestPaths component renders a suggestion to select a node when
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              const container = document.getElementById("container");
 
@@ -33,7 +34,7 @@ Test that the ShortestPaths component renders a suggestion to select a node when
 
              ok(container.textContent.includes(L10N.getStr("shortest-paths.select-node")),
                 "The node selection prompt is displayed");
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_SnapshotListItem_01.html b/devtools/client/memory/test/chrome/test_SnapshotListItem_01.html
index f4796c97e482..b1b7875e8ef3 100644
--- a/devtools/client/memory/test/chrome/test_SnapshotListItem_01.html
+++ b/devtools/client/memory/test/chrome/test_SnapshotListItem_01.html
@@ -16,37 +16,37 @@ path.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
-          try {
-            const container = document.getElementById("container");
+          "use strict";
+          window.onload = async function() {
+            try {
+              const container = document.getElementById("container");
 
-            await renderComponent(
-              SnapshotListItem(TEST_SNAPSHOT_LIST_ITEM_PROPS),
-              container
-            );
+              await renderComponent(
+                SnapshotListItem(TEST_SNAPSHOT_LIST_ITEM_PROPS),
+                container
+              );
 
-            ok(container.querySelector('.delete'),
-               "Should have delete button when there is a path");
+              ok(container.querySelector(".delete"),
+                 "Should have delete button when there is a path");
 
-            const pathlessProps = immutableUpdate(
-                TEST_SNAPSHOT_LIST_ITEM_PROPS,
-                {item: immutableUpdate(TEST_SNAPSHOT, {path: null})}
-            );
+              const pathlessProps = immutableUpdate(
+                  TEST_SNAPSHOT_LIST_ITEM_PROPS,
+                  {item: immutableUpdate(TEST_SNAPSHOT, {path: null})}
+              );
 
-            await renderComponent(
-              SnapshotListItem(pathlessProps),
-              container
-            );
+              await renderComponent(
+                SnapshotListItem(pathlessProps),
+                container
+              );
 
-            ok(!container.querySelector('.delete'),
-               "No delete button should be found if there is no path\n");
-
-          } catch(e) {
-            ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
-          } finally {
-            SimpleTest.finish();
-          }
-         };
+              ok(!container.querySelector(".delete"),
+                 "No delete button should be found if there is no path\n");
+            } catch (e) {
+              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
+            } finally {
+              SimpleTest.finish();
+            }
+          };
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_Toolbar_01.html b/devtools/client/memory/test/chrome/test_Toolbar_01.html
index c2c234e09e90..33f0326d9fc4 100644
--- a/devtools/client/memory/test/chrome/test_Toolbar_01.html
+++ b/devtools/client/memory/test/chrome/test_Toolbar_01.html
@@ -14,13 +14,14 @@ Test that the Toolbar component shows the view switcher only at the appropriate
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         "use strict";
+         window.onload = async function() {
            try {
              const container = document.getElementById("container");
 
              // Census and dominator tree views.
 
-             for (let view of [viewState.CENSUS, viewState.DOMINATOR_TREE]) {
+             for (const view of [viewState.CENSUS, viewState.DOMINATOR_TREE]) {
                await renderComponent(Toolbar(immutableUpdate(TEST_TOOLBAR_PROPS, {
                  view: { state: view },
                })), container);
@@ -35,7 +36,7 @@ Test that the Toolbar component shows the view switcher only at the appropriate
 
              ok(!container.querySelector("#select-view"),
                 "The view selector is NOT shown in the DIFFING view");
-           } catch(e) {
+           } catch (e) {
              ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
            } finally {
              SimpleTest.finish();
diff --git a/devtools/client/memory/test/chrome/test_TreeMap_01.html b/devtools/client/memory/test/chrome/test_TreeMap_01.html
index 15be48b5e164..5f45e2e9d1a8 100644
--- a/devtools/client/memory/test/chrome/test_TreeMap_01.html
+++ b/devtools/client/memory/test/chrome/test_TreeMap_01.html
@@ -20,19 +20,19 @@ Test that the Tree Map correctly renders onto 2 managed canvases.
   <pre id="test">
     <script src="head.js" type="application/javascript"></script>
     <script type="application/javascript">
-      window.onload = async function () {
+      "use strict";
+      window.onload = async function() {
         try {
           const container = document.getElementById("container");
 
           await renderComponent(TreeMap(TEST_TREE_MAP_PROPS), container);
 
-          let treeMapContainer = container.querySelector(".tree-map-container");
+          const treeMapContainer = container.querySelector(".tree-map-container");
           ok(treeMapContainer, "Component creates a container");
 
-          let canvases = treeMapContainer.querySelectorAll("canvas");
+          const canvases = treeMapContainer.querySelectorAll("canvas");
           is(canvases.length, 2, "Creates 2 canvases");
-
-        } catch(e) {
+        } catch (e) {
           ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
         } finally {
           SimpleTest.finish();