diff --git a/.eslintignore b/.eslintignore
index 15ca6febda18..7df403a5557b 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -59,9 +59,6 @@ devtools/client/performance/components/test/test_jit_optimizations_01.html
 devtools/server/tests/browser/storage-*.html
 !devtools/server/tests/browser/storage-unsecured-iframe.html
 devtools/server/tests/browser/stylesheets-nested-iframes.html
-devtools/shared/qrcode/tests/mochitest/test_decode.html
-devtools/shared/tests/mochitest/*.html
-devtools/shared/webconsole/test/test_*.html
 devtools/client/webreplay/mochitest/examples/*.html
 
 # Ignore devtools debugger files
diff --git a/devtools/.eslintrc.js b/devtools/.eslintrc.js
index a63d8991ef2e..af410087459b 100644
--- a/devtools/.eslintrc.js
+++ b/devtools/.eslintrc.js
@@ -48,6 +48,7 @@ module.exports = {
       "client/framework/**",
       "client/shared/*.jsm",
       "client/shared/widgets/*.jsm",
+      "shared/webconsole/test/*.html",
     ],
     "rules": {
       "mozilla/no-aArgs": "off",
diff --git a/devtools/shared/qrcode/tests/mochitest/test_decode.html b/devtools/shared/qrcode/tests/mochitest/test_decode.html
index d5354e89ced9..73c84944c8dd 100644
--- a/devtools/shared/qrcode/tests/mochitest/test_decode.html
+++ b/devtools/shared/qrcode/tests/mochitest/test_decode.html
@@ -10,7 +10,10 @@ Test decoding a simple message
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
   <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css">
   <script type="application/javascript">
+"use strict";
+
 window.onload = function() {
+
   const { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm");
 
   const QR = require("devtools/shared/qrcode/index");
diff --git a/devtools/shared/tests/mochitest/test_css-logic-findCssSelector.html b/devtools/shared/tests/mochitest/test_css-logic-findCssSelector.html
index f41f82854c95..a47cf07a54d5 100644
--- a/devtools/shared/tests/mochitest/test_css-logic-findCssSelector.html
+++ b/devtools/shared/tests/mochitest/test_css-logic-findCssSelector.html
@@ -7,6 +7,7 @@
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
   <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css">
   <script type="application/javascript">
+"use strict";
 
 const { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm");
 const { findCssSelector } = require("devtools/shared/inspector/css-logic");
@@ -30,10 +31,10 @@ window.onload = function() {
 };
 
 addTest(function findAllCssSelectors() {
-  var nodes = document.querySelectorAll("*");
-  for (var i = 0; i < nodes.length; i++) {
-    var selector = findCssSelector(nodes[i]);
-    var matches = document.querySelectorAll(selector);
+  const nodes = document.querySelectorAll("*");
+  for (let i = 0; i < nodes.length; i++) {
+    const selector = findCssSelector(nodes[i]);
+    const matches = document.querySelectorAll(selector);
 
     is(matches.length, 1, "There is a single match: " + selector);
     is(matches[0], nodes[i], "The selector matches the correct node: " + selector);
@@ -43,22 +44,22 @@ addTest(function findAllCssSelectors() {
 });
 
 addTest(function findCssSelectorNotContainedInDocument() {
-  var unattached = document.createElement("div");
+  const unattached = document.createElement("div");
   unattached.id = "unattached";
   is(findCssSelector(unattached), "", "Unattached node returns empty string");
 
-  var unattachedChild = document.createElement("div");
+  const unattachedChild = document.createElement("div");
   unattached.appendChild(unattachedChild);
   is(findCssSelector(unattachedChild), "", "Unattached child returns empty string");
 
-  var unattachedBody = document.createElement("body");
+  const unattachedBody = document.createElement("body");
   is(findCssSelector(unattachedBody), "", "Unattached body returns empty string");
 
   runNextTest();
 });
 
 addTest(function findCssSelectorBasic() {
-  let data = [
+  const data = [
     "#one",
     "#" + CSS.escape("2"),
     ".three",
@@ -75,11 +76,11 @@ addTest(function findCssSelectorBasic() {
     "#" + CSS.escape("!, \", #, $, %, &, ', (, ), *, +, ,, -, ., /, :, ;, <, =, >, ?, @, [, \\, ], ^, `, {, |, }, ~"),
   ];
 
-  let container = document.querySelector("#find-css-selector");
+  const container = document.querySelector("#find-css-selector");
   is(container.children.length, data.length, "Container has correct number of children.");
 
   for (let i = 0; i < data.length; i++) {
-    let node = container.children[i];
+    const node = container.children[i];
     is(findCssSelector(node), data[i], "matched id for index " + (i - 1));
   }
 
diff --git a/devtools/shared/tests/mochitest/test_css-logic-getCssPath.html b/devtools/shared/tests/mochitest/test_css-logic-getCssPath.html
index 5665ce57f4ed..a74b704ca0b3 100644
--- a/devtools/shared/tests/mochitest/test_css-logic-getCssPath.html
+++ b/devtools/shared/tests/mochitest/test_css-logic-getCssPath.html
@@ -10,6 +10,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1323700
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
   <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css">
   <script type="application/javascript">
+"use strict";
 
 const { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm");
 const CssLogic = require("devtools/shared/inspector/css-logic");
@@ -33,15 +34,15 @@ window.onload = function() {
 }
 
 addTest(function getCssPathForUnattachedElement() {
-  var unattached = document.createElement("div");
+  const unattached = document.createElement("div");
   unattached.id = "unattached";
   is(CssLogic.getCssPath(unattached), "", "Unattached node returns empty string");
 
-  var unattachedChild = document.createElement("div");
+  const unattachedChild = document.createElement("div");
   unattached.appendChild(unattachedChild);
   is(CssLogic.getCssPath(unattachedChild), "", "Unattached child returns empty string");
 
-  var unattachedBody = document.createElement("body");
+  const unattachedBody = document.createElement("body");
   is(CssLogic.getCssPath(unattachedBody), "", "Unattached body returns empty string");
 
   runNextTest();
@@ -52,7 +53,7 @@ addTest(function cssPathHasOneStepForEachAncestor() {
     const splitPath = CssLogic.getCssPath(el).split(" ");
 
     let expectedNbOfParts = 0;
-    var parent = el.parentNode;
+    let parent = el.parentNode;
     while (parent) {
       expectedNbOfParts ++;
       parent = parent.parentNode;
diff --git a/devtools/shared/webconsole/test/test_basics.html b/devtools/shared/webconsole/test/test_basics.html
index ec73c2024977..ecb4a726c17e 100644
--- a/devtools/shared/webconsole/test/test_basics.html
+++ b/devtools/shared/webconsole/test/test_basics.html
@@ -12,6 +12,8 @@
 <p>Basic Web Console Actor tests</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 function startTest()
diff --git a/devtools/shared/webconsole/test/test_bug819670_getter_throws.html b/devtools/shared/webconsole/test/test_bug819670_getter_throws.html
index 1eff6b52b239..6e5daba29ca6 100644
--- a/devtools/shared/webconsole/test/test_bug819670_getter_throws.html
+++ b/devtools/shared/webconsole/test/test_bug819670_getter_throws.html
@@ -12,6 +12,8 @@
 <p>Test for Bug 819670 - Web console object inspection does not handle native getters throwing very well</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 function startTest()
@@ -48,6 +50,7 @@ function onInspect(aState, aResponse)
 {
   ok(!aResponse.error, "no response error");
 
+  // eslint-disable-next-line no-proto
   const expectedProps =  Object.getOwnPropertyNames(document.__proto__);
 
   const props = aResponse.ownProperties;
diff --git a/devtools/shared/webconsole/test/test_cached_messages.html b/devtools/shared/webconsole/test/test_cached_messages.html
index 8a897295a6e8..2730db212814 100644
--- a/devtools/shared/webconsole/test/test_cached_messages.html
+++ b/devtools/shared/webconsole/test/test_cached_messages.html
@@ -12,6 +12,8 @@
 <p>Test for cached messages</p>
 
 <script class="testbody" type="application/javascript">
+"use strict";
+
 window.docShell.cssErrorReportingEnabled = true;
 var ConsoleAPIStorage = Cc["@mozilla.org/consoleAPI-storage;1"]
                           .getService(Ci.nsIConsoleAPIStorage);
@@ -96,6 +98,8 @@ function doConsoleCalls() {
 </script>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 var {ConsoleServiceListener} =
   require("devtools/server/actors/webconsole/listeners/console-service");
diff --git a/devtools/shared/webconsole/test/test_commands_other.html b/devtools/shared/webconsole/test/test_commands_other.html
index 24c9fa9e9c10..a224ccc9bba2 100644
--- a/devtools/shared/webconsole/test/test_commands_other.html
+++ b/devtools/shared/webconsole/test/test_commands_other.html
@@ -12,29 +12,12 @@
 <p>Test for the querySelector / querySelectorAll helpers</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 let gState;
 let gWin;
-let tests;
-
-function evaluateJS(input) {
-  return gState.webConsoleFront.evaluateJSAsync(input);
-}
-
-function startTest() {
-  info ("Content window opened, attaching console to it");
-
-  const systemPrincipal = Cc["@mozilla.org/systemprincipal;1"].createInstance(Ci.nsIPrincipal);
-  ok (!gWin.document.nodePrincipal.equals(systemPrincipal),
-      "The test document is not using the system principal");
-
-  attachConsoleToTab([], state => {
-    gState = state;
-    runTests(tests, testEnd);
-  });
-}
-
-tests = [
+const tests = [
   async function keys() {
     const response = await evaluateJS("keys({foo: 'bar'})");
     checkObject(response, {
@@ -61,6 +44,23 @@ tests = [
   },
 ];
 
+function evaluateJS(input) {
+  return gState.webConsoleFront.evaluateJSAsync(input);
+}
+
+function startTest() {
+  info ("Content window opened, attaching console to it");
+
+  const systemPrincipal = Cc["@mozilla.org/systemprincipal;1"].createInstance(Ci.nsIPrincipal);
+  ok (!gWin.document.nodePrincipal.equals(systemPrincipal),
+      "The test document is not using the system principal");
+
+  attachConsoleToTab([], state => {
+    gState = state;
+    runTests(tests, testEnd);
+  });
+}
+
 function testEnd() {
   gWin.close();
   gWin = null;
diff --git a/devtools/shared/webconsole/test/test_console_group_styling.html b/devtools/shared/webconsole/test/test_console_group_styling.html
index 23fa5f4e9f6f..642801adc1ac 100644
--- a/devtools/shared/webconsole/test/test_console_group_styling.html
+++ b/devtools/shared/webconsole/test/test_console_group_styling.html
@@ -10,8 +10,6 @@
   <script>
 "use strict";
 
-const TEST_URL = "data:text/html,<html><body>Hello</body></html>";
-
 window.onload = async function () {
   SimpleTest.waitForExplicitFinish();
   let state;
diff --git a/devtools/shared/webconsole/test/test_console_serviceworker.html b/devtools/shared/webconsole/test/test_console_serviceworker.html
index 224253cdfe8b..3aae944a74ac 100644
--- a/devtools/shared/webconsole/test/test_console_serviceworker.html
+++ b/devtools/shared/webconsole/test/test_console_serviceworker.html
@@ -12,6 +12,8 @@
 <p>Test for the Console API and Service Workers</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 // Utils functions
diff --git a/devtools/shared/webconsole/test/test_console_serviceworker_cached.html b/devtools/shared/webconsole/test/test_console_serviceworker_cached.html
index d593ebd5212b..274cd8b96c7b 100644
--- a/devtools/shared/webconsole/test/test_console_serviceworker_cached.html
+++ b/devtools/shared/webconsole/test/test_console_serviceworker_cached.html
@@ -12,6 +12,8 @@
 <p>Test for getCachedMessages and Service Workers</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 const BASE_URL = "https://example.com/chrome/devtools/shared/webconsole/test/";
@@ -73,7 +75,8 @@ const startTest = async function () {
   // they shouldn't show up in a call to getCachedMessages.
   // However, there is a fetch event which is logged due to loading the tab.
   info("Adding a new tab at the same URL");
-  const tab2 = await addTab(FRAME_URL);
+
+  await addTab(FRAME_URL);
   await new Promise(resolve => {
     info("Attaching console to tab 2");
     attachConsoleToTab(["ConsoleAPI"], function(state) {
diff --git a/devtools/shared/webconsole/test/test_console_styling.html b/devtools/shared/webconsole/test/test_console_styling.html
index 7dba35a1ee1a..2c6fc4e263fd 100644
--- a/devtools/shared/webconsole/test/test_console_styling.html
+++ b/devtools/shared/webconsole/test/test_console_styling.html
@@ -12,6 +12,8 @@
 <p>Test for console.log styling with %c</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 let expectedConsoleCalls = [];
diff --git a/devtools/shared/webconsole/test/test_console_timestamp.html b/devtools/shared/webconsole/test/test_console_timestamp.html
index 35d51455e49b..d56774ee0e31 100644
--- a/devtools/shared/webconsole/test/test_console_timestamp.html
+++ b/devtools/shared/webconsole/test/test_console_timestamp.html
@@ -10,8 +10,6 @@
   <script>
 "use strict";
 
-const TEST_URL = "data:text/html,<html>Test ConsoleAPI timestamp correctness";
-
 window.onload = async function () {
   SimpleTest.waitForExplicitFinish();
   let state;
diff --git a/devtools/shared/webconsole/test/test_console_worker.html b/devtools/shared/webconsole/test/test_console_worker.html
index 27433f2b8ab7..bda27fac165f 100644
--- a/devtools/shared/webconsole/test/test_console_worker.html
+++ b/devtools/shared/webconsole/test/test_console_worker.html
@@ -12,6 +12,8 @@
 <p>Test for the Console API and Workers</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 const expectedCachedConsoleCalls = [
@@ -30,9 +32,9 @@ const expectedConsoleAPICalls = [
 ];
 
 window.onload = async function () {
-  const {state,response} = await new Promise(resolve => {
-    attachConsoleToWorker(["ConsoleAPI"], (state, response) => {
-      resolve({state,response})
+  const {state} = await new Promise(resolve => {
+    attachConsoleToWorker(["ConsoleAPI"], (s) => {
+      resolve({state: s})
     });
   });
 
diff --git a/devtools/shared/webconsole/test/test_consoleapi.html b/devtools/shared/webconsole/test/test_consoleapi.html
index f6ea0e2e47ef..bef7e9308590 100644
--- a/devtools/shared/webconsole/test/test_consoleapi.html
+++ b/devtools/shared/webconsole/test/test_consoleapi.html
@@ -12,6 +12,8 @@
 <p>Test for the Console API</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 let expectedConsoleCalls = [];
@@ -43,8 +45,7 @@ function doConsoleCalls(aState)
 
   (function(global, foreign) {
     "use asm";
-    var fromAsmJS = foreign.fromAsmJS;
-    function inAsmJS2() { fromAsmJS() }
+    function inAsmJS2() { foreign.fromAsmJS() }
     function inAsmJS1() { inAsmJS2() }
     return inAsmJS1
   })(null, { fromAsmJS:fromAsmJS })();
diff --git a/devtools/shared/webconsole/test/test_consoleapi_innerID.html b/devtools/shared/webconsole/test/test_consoleapi_innerID.html
index 7b08d58b829f..866e2092fda2 100644
--- a/devtools/shared/webconsole/test/test_consoleapi_innerID.html
+++ b/devtools/shared/webconsole/test/test_consoleapi_innerID.html
@@ -12,6 +12,8 @@
 <p>Test for the Console API</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 let expectedConsoleCalls = [];
diff --git a/devtools/shared/webconsole/test/test_file_uri.html b/devtools/shared/webconsole/test/test_file_uri.html
index 67f926180617..ae838d285c11 100644
--- a/devtools/shared/webconsole/test/test_file_uri.html
+++ b/devtools/shared/webconsole/test/test_file_uri.html
@@ -12,6 +12,8 @@
 <p>Test for file activity tracking</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 const {NetUtil} = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
diff --git a/devtools/shared/webconsole/test/test_jsterm.html b/devtools/shared/webconsole/test/test_jsterm.html
index c2d5ebdfb89f..8c016475e8a9 100644
--- a/devtools/shared/webconsole/test/test_jsterm.html
+++ b/devtools/shared/webconsole/test/test_jsterm.html
@@ -14,6 +14,8 @@
 <iframe id="content-iframe" src="http://example.com/chrome/devtools/shared/webconsole/test/sandboxed_iframe.html"></iframe>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 let gState;
@@ -181,7 +183,7 @@ async function doEvalWithBindingFrame() {
   const iframeObjectActor = response.result.actor;
   ok(iframeObjectActor, "There is an actor associated with the response");
 
-  const selectedObjectGlobal = await evaluateJS("this.temp1 = _self;", {
+  await evaluateJS("this.temp1 = _self;", {
     selectedObjectActor: iframeObjectActor
   });
   ok(top.temp1 && top.temp1.bar === 1,
diff --git a/devtools/shared/webconsole/test/test_jsterm_autocomplete.html b/devtools/shared/webconsole/test/test_jsterm_autocomplete.html
index e8b08039f483..6ab6c489a6f5 100644
--- a/devtools/shared/webconsole/test/test_jsterm_autocomplete.html
+++ b/devtools/shared/webconsole/test/test_jsterm_autocomplete.html
@@ -12,6 +12,8 @@
 <p>Test for JavaScript terminal autocomplete functionality</p>
 
 <script class="testbody" type="text/javascript">
+  "use strict";
+
   SimpleTest.waitForExplicitFinish();
   const {
     MAX_AUTOCOMPLETE_ATTEMPTS,
diff --git a/devtools/shared/webconsole/test/test_jsterm_cd_iframe.html b/devtools/shared/webconsole/test/test_jsterm_cd_iframe.html
index 5b724e8761ee..f4ac61015344 100644
--- a/devtools/shared/webconsole/test/test_jsterm_cd_iframe.html
+++ b/devtools/shared/webconsole/test/test_jsterm_cd_iframe.html
@@ -14,6 +14,8 @@
 <iframe id="content-iframe" src="http://example.com/chrome/devtools/shared/webconsole/test/sandboxed_iframe.html"></iframe>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 let gState;
diff --git a/devtools/shared/webconsole/test/test_jsterm_last_result.html b/devtools/shared/webconsole/test/test_jsterm_last_result.html
index 9218aac35486..cc55c3e5bf03 100644
--- a/devtools/shared/webconsole/test/test_jsterm_last_result.html
+++ b/devtools/shared/webconsole/test/test_jsterm_last_result.html
@@ -14,6 +14,8 @@
 <iframe id="content-iframe" src="http://example.com/chrome/devtools/shared/webconsole/test/sandboxed_iframe.html"></iframe>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 let gState;
 
diff --git a/devtools/shared/webconsole/test/test_jsterm_queryselector.html b/devtools/shared/webconsole/test/test_jsterm_queryselector.html
index 1de4ff1409c6..181aa38a2e4a 100644
--- a/devtools/shared/webconsole/test/test_jsterm_queryselector.html
+++ b/devtools/shared/webconsole/test/test_jsterm_queryselector.html
@@ -12,6 +12,8 @@
 <p>Test for the querySelector / querySelectorAll helpers</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 let gState;
 let gWin;
diff --git a/devtools/shared/webconsole/test/test_network_get.html b/devtools/shared/webconsole/test/test_network_get.html
index ad63aed59947..3427a50ffa7c 100644
--- a/devtools/shared/webconsole/test/test_network_get.html
+++ b/devtools/shared/webconsole/test/test_network_get.html
@@ -14,6 +14,8 @@
 <iframe src="http://example.com/chrome/devtools/shared/webconsole/test/network_requests_iframe.html"></iframe>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 function startTest()
diff --git a/devtools/shared/webconsole/test/test_network_post.html b/devtools/shared/webconsole/test/test_network_post.html
index 6745bebd263c..8e269e30d2df 100644
--- a/devtools/shared/webconsole/test/test_network_post.html
+++ b/devtools/shared/webconsole/test/test_network_post.html
@@ -14,6 +14,8 @@
 <iframe src="http://example.com/chrome/devtools/shared/webconsole/test/network_requests_iframe.html"></iframe>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 function startTest()
diff --git a/devtools/shared/webconsole/test/test_network_security-hpkp.html b/devtools/shared/webconsole/test/test_network_security-hpkp.html
index 1b7088ffb103..331c42f07737 100644
--- a/devtools/shared/webconsole/test/test_network_security-hpkp.html
+++ b/devtools/shared/webconsole/test/test_network_security-hpkp.html
@@ -14,6 +14,8 @@
 <iframe src="https://example.com/chrome/devtools/shared/webconsole/test/network_requests_iframe.html"></iframe>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 let gCurrentTestCase = -1;
@@ -51,8 +53,7 @@ function startTest() {
     const gSSService = Cc["@mozilla.org/ssservice;1"]
                        .getService(Ci.nsISiteSecurityService);
 
-    const gIOService = Cc["@mozilla.org/network/io-service;1"]
-                       .getService(Ci.nsIIOService);
+    const gIOService = Services.io;
     for (const {url} of TEST_CASES) {
       const uri = gIOService.newURI(url);
       gSSService.resetState(Ci.nsISiteSecurityService.HEADER_HPKP, uri, 0);
diff --git a/devtools/shared/webconsole/test/test_network_security-hsts.html b/devtools/shared/webconsole/test/test_network_security-hsts.html
index e45fac937621..092300564cda 100644
--- a/devtools/shared/webconsole/test/test_network_security-hsts.html
+++ b/devtools/shared/webconsole/test/test_network_security-hsts.html
@@ -14,6 +14,8 @@
 <iframe src="https://example.com/chrome/devtools/shared/webconsole/test/network_requests_iframe.html"></iframe>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 let gCurrentTestCase = -1;
@@ -44,8 +46,7 @@ function startTest()
     const gSSService = Cc["@mozilla.org/ssservice;1"]
                        .getService(Ci.nsISiteSecurityService);
 
-    const gIOService = Cc["@mozilla.org/network/io-service;1"]
-                       .getService(Ci.nsIIOService);
+    const gIOService = Services.io;
 
     const uri = gIOService.newURI(TEST_CASES[0].url);
     gSSService.resetState(Ci.nsISiteSecurityService.HEADER_HSTS, uri, 0);
diff --git a/devtools/shared/webconsole/test/test_object_actor.html b/devtools/shared/webconsole/test/test_object_actor.html
index e84ce95a1ace..7e05ea903191 100644
--- a/devtools/shared/webconsole/test/test_object_actor.html
+++ b/devtools/shared/webconsole/test/test_object_actor.html
@@ -12,6 +12,8 @@
 <p>Test for the object actor</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 SpecialPowers.pushPrefEnv({"set": [["security.allow_eval_with_system_principal",
diff --git a/devtools/shared/webconsole/test/test_object_actor_native_getters.html b/devtools/shared/webconsole/test/test_object_actor_native_getters.html
index 789b30ad4ea4..2dbef501f574 100644
--- a/devtools/shared/webconsole/test/test_object_actor_native_getters.html
+++ b/devtools/shared/webconsole/test/test_object_actor_native_getters.html
@@ -12,6 +12,8 @@
 <p>Test for the native getters in object actors</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 let expectedProps = [];
diff --git a/devtools/shared/webconsole/test/test_object_actor_native_getters_lenient_this.html b/devtools/shared/webconsole/test/test_object_actor_native_getters_lenient_this.html
index d43a75813418..c8c3e54348eb 100644
--- a/devtools/shared/webconsole/test/test_object_actor_native_getters_lenient_this.html
+++ b/devtools/shared/webconsole/test/test_object_actor_native_getters_lenient_this.html
@@ -13,6 +13,8 @@
 <p>Test for the native getters in object actors</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 function startTest()
diff --git a/devtools/shared/webconsole/test/test_page_errors.html b/devtools/shared/webconsole/test/test_page_errors.html
index 1eeb7d9fa584..b0e8b178615a 100644
--- a/devtools/shared/webconsole/test/test_page_errors.html
+++ b/devtools/shared/webconsole/test/test_page_errors.html
@@ -12,6 +12,8 @@
 <p>Test for page errors</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 let expectedPageErrors = [];
diff --git a/devtools/shared/webconsole/test/test_throw.html b/devtools/shared/webconsole/test/test_throw.html
index 82eaf332a3e3..3b0716765ffe 100644
--- a/devtools/shared/webconsole/test/test_throw.html
+++ b/devtools/shared/webconsole/test/test_throw.html
@@ -12,6 +12,8 @@
 <p>Web Console throw tests</p>
 
 <script class="testbody" type="text/javascript">
+"use strict";
+
 SimpleTest.waitForExplicitFinish();
 
 function startTest()
@@ -20,15 +22,15 @@ function startTest()
   attachConsoleToTab([], onAttach);
 }
 
-function onAttach(aState, aResponse)
+function onAttach(aState)
 {
   const tests = [];
 
   const falsyValues = ["-0", "null", "undefined", "Infinity", "-Infinity", "NaN"];
   falsyValues.forEach(function(value) {
     tests.push(async function() {
-      const aResponse = await aState.webConsoleFront.evaluateJSAsync("throw " + value + ";")
-      const type = aResponse.exception.type;
+      const response = await aState.webConsoleFront.evaluateJSAsync("throw " + value + ";")
+      const type = response.exception.type;
       is(type, value, "exception.type for throw " + value);
       nextTest();
     });
@@ -37,8 +39,8 @@ function onAttach(aState, aResponse)
   const identityTestValues = [false, 0];
   identityTestValues.forEach(function(value) {
     tests.push(async function() {
-      const aResponse = await aState.webConsoleFront.evaluateJSAsync("throw " + value + ";")
-      const exception = aResponse.exception;
+      const response = await aState.webConsoleFront.evaluateJSAsync("throw " + value + ";")
+      const exception = response.exception;
       is(exception, value, "response.exception for throw " + value);
       nextTest();
     });
@@ -49,11 +51,11 @@ function onAttach(aState, aResponse)
                         DebuggerServer.LONG_STRING_INITIAL_LENGTH
                       );
   tests.push(async function() {
-    const aResponse = await aState.webConsoleFront.evaluateJSAsync("throw '" + longString + "';")
-    is(aResponse.exception.initial, shortedString,
+    const response = await aState.webConsoleFront.evaluateJSAsync("throw '" + longString + "';")
+    is(response.exception.initial, shortedString,
       "exception.initial for throw longString"
     );
-    is(aResponse.exceptionMessage.initial, shortedString,
+    is(response.exceptionMessage.initial, shortedString,
       "exceptionMessage.initial for throw longString"
     );
     nextTest();
@@ -66,8 +68,8 @@ function onAttach(aState, aResponse)
   ];
   symbolTestValues.forEach(function([expr, message]) {
     tests.push(async function() {
-      const aResponse = await aState.webConsoleFront.evaluateJSAsync("throw " + expr + ";");
-      is(aResponse.exceptionMessage, message,
+      const response = await aState.webConsoleFront.evaluateJSAsync("throw " + expr + ";");
+      is(response.exceptionMessage, message,
          "response.exception for throw " + expr);
       nextTest();
     });