diff --git a/js/src/builtin/Eval.cpp b/js/src/builtin/Eval.cpp
index 49e7e2cd771a..bdf61f3bf27e 100644
--- a/js/src/builtin/Eval.cpp
+++ b/js/src/builtin/Eval.cpp
@@ -330,12 +330,7 @@ static bool EvalKernel(JSContext* cx, HandleValue v, EvalType evalType,
     }
 
     SourceText<char16_t> srcBuf;
-
-    const char16_t* chars = linearChars.twoByteRange().begin().get();
-    SourceOwnership ownership = linearChars.maybeGiveOwnershipToCaller()
-                                    ? SourceOwnership::TakeOwnership
-                                    : SourceOwnership::Borrowed;
-    if (!srcBuf.init(cx, chars, linearStr->length(), ownership)) {
+    if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
       return false;
     }
 
diff --git a/js/src/builtin/ShadowRealm.cpp b/js/src/builtin/ShadowRealm.cpp
index 23656bd298e5..adc7f3c2459f 100644
--- a/js/src/builtin/ShadowRealm.cpp
+++ b/js/src/builtin/ShadowRealm.cpp
@@ -222,12 +222,7 @@ static bool PerformShadowRealmEval(JSContext* cx, Handle<JSString*> sourceText,
       return false;
     }
     SourceText<char16_t> srcBuf;
-
-    const char16_t* chars = linearChars.twoByteRange().begin().get();
-    SourceOwnership ownership = linearChars.maybeGiveOwnershipToCaller()
-                                    ? SourceOwnership::TakeOwnership
-                                    : SourceOwnership::Borrowed;
-    if (!srcBuf.init(cx, chars, linearChars.length(), ownership)) {
+    if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
       return false;
     }
 
diff --git a/js/src/builtin/TestingFunctions.cpp b/js/src/builtin/TestingFunctions.cpp
index a5b77943feda..f44090dc6170 100644
--- a/js/src/builtin/TestingFunctions.cpp
+++ b/js/src/builtin/TestingFunctions.cpp
@@ -6131,15 +6131,6 @@ static bool EvalReturningScope(JSContext* cx, unsigned argc, Value* vp) {
     }
   }
 
-  AutoStableStringChars strChars(cx);
-  if (!strChars.initTwoByte(cx, str)) {
-    return false;
-  }
-
-  mozilla::Range<const char16_t> chars = strChars.twoByteRange();
-  size_t srclen = chars.length();
-  const char16_t* src = chars.begin().get();
-
   JS::AutoFilename filename;
   unsigned lineno;
 
@@ -6150,8 +6141,12 @@ static bool EvalReturningScope(JSContext* cx, unsigned argc, Value* vp) {
   options.setNoScriptRval(true);
   options.setNonSyntacticScope(true);
 
+  AutoStableStringChars linearChars(cx);
+  if (!linearChars.initTwoByte(cx, str)) {
+    return false;
+  }
   JS::SourceText<char16_t> srcBuf;
-  if (!srcBuf.init(cx, src, srclen, SourceOwnership::Borrowed)) {
+  if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
     return false;
   }
 
@@ -6362,8 +6357,7 @@ static bool CompileToStencil(JSContext* cx, uint32_t argc, Value* vp) {
     return false;
   }
   JS::SourceText<char16_t> srcBuf;
-  if (!srcBuf.init(cx, linearChars.twoByteChars(), src->length(),
-                   JS::SourceOwnership::Borrowed)) {
+  if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
     return false;
   }
 
@@ -6508,8 +6502,7 @@ static bool CompileToStencilXDR(JSContext* cx, uint32_t argc, Value* vp) {
     return false;
   }
   JS::SourceText<char16_t> srcBuf;
-  if (!srcBuf.init(cx, linearChars.twoByteChars(), src->length(),
-                   JS::SourceOwnership::Borrowed)) {
+  if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
     return false;
   }
 
@@ -7694,20 +7687,13 @@ JSScript* js::TestingFunctionArgumentToScript(
     JSContext* cx, HandleValue v, JSFunction** funp /* = nullptr */) {
   if (v.isString()) {
     // To convert a string to a script, compile it. Parse it as an ES6 Program.
-    Rooted<JSLinearString*> linearStr(
-        cx, JS::StringToLinearString(cx, v.toString()));
-    if (!linearStr) {
-      return nullptr;
-    }
-    size_t len = JS::GetLinearStringLength(linearStr);
+    Rooted<JSString*> str(cx, v.toString());
     AutoStableStringChars linearChars(cx);
-    if (!linearChars.initTwoByte(cx, linearStr)) {
+    if (!linearChars.initTwoByte(cx, str)) {
       return nullptr;
     }
-    const char16_t* chars = linearChars.twoByteRange().begin().get();
-
     SourceText<char16_t> source;
-    if (!source.init(cx, chars, len, SourceOwnership::Borrowed)) {
+    if (!source.initMaybeBorrowed(cx, linearChars)) {
       return nullptr;
     }
 
diff --git a/js/src/debugger/Object.cpp b/js/src/debugger/Object.cpp
index 92266e1b4c3e..0b40f96e76a7 100644
--- a/js/src/debugger/Object.cpp
+++ b/js/src/debugger/Object.cpp
@@ -1287,14 +1287,12 @@ bool DebuggerObject::CallData::createSource() {
     compileOptions.setIntroductionType("inlineScript");
   }
 
-  Vector<char16_t> textChars(cx);
-  if (!CopyStringToVector(cx, text, textChars)) {
+  AutoStableStringChars linearChars(cx);
+  if (!linearChars.initTwoByte(cx, text)) {
     return false;
   }
-
   JS::SourceText<char16_t> srcBuf;
-  if (!srcBuf.init(cx, textChars.begin(), text->length(),
-                   JS::SourceOwnership::Borrowed)) {
+  if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
     return false;
   }
 
diff --git a/js/src/shell/ModuleLoader.cpp b/js/src/shell/ModuleLoader.cpp
index e95341eacf89..058248bc5956 100644
--- a/js/src/shell/ModuleLoader.cpp
+++ b/js/src/shell/ModuleLoader.cpp
@@ -469,15 +469,13 @@ JSObject* ModuleLoader::loadAndParse(JSContext* cx, HandleString pathArg) {
     return nullptr;
   }
 
-  JS::AutoStableStringChars stableChars(cx);
-  if (!stableChars.initTwoByte(cx, source)) {
+  JS::AutoStableStringChars linearChars(cx);
+  if (!linearChars.initTwoByte(cx, source)) {
     return nullptr;
   }
 
-  const char16_t* chars = stableChars.twoByteRange().begin().get();
   JS::SourceText<char16_t> srcBuf;
-  if (!srcBuf.init(cx, chars, source->length(),
-                   JS::SourceOwnership::Borrowed)) {
+  if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
     return nullptr;
   }
 
diff --git a/js/src/shell/js.cpp b/js/src/shell/js.cpp
index 904b63e6dfcd..41e2088723fc 100644
--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -2409,15 +2409,13 @@ static bool Evaluate(JSContext* cx, unsigned argc, Value* vp) {
         return false;
       }
     } else {
-      AutoStableStringChars codeChars(cx);
-      if (!codeChars.initTwoByte(cx, code)) {
+      AutoStableStringChars linearChars(cx);
+      if (!linearChars.initTwoByte(cx, code)) {
         return false;
       }
-      mozilla::Range<const char16_t> chars = codeChars.twoByteRange();
 
       JS::SourceText<char16_t> srcBuf;
-      if (!srcBuf.init(cx, chars.begin().get(), chars.length(),
-                       JS::SourceOwnership::Borrowed)) {
+      if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
         return false;
       }
 
@@ -2629,14 +2627,13 @@ static bool Run(JSContext* cx, unsigned argc, Value* vp) {
     return false;
   }
 
-  AutoStableStringChars chars(cx);
-  if (!chars.initTwoByte(cx, str)) {
+  AutoStableStringChars linearChars(cx);
+  if (!linearChars.initTwoByte(cx, str)) {
     return false;
   }
 
   JS::SourceText<char16_t> srcBuf;
-  if (!srcBuf.init(cx, chars.twoByteRange().begin().get(), str->length(),
-                   JS::SourceOwnership::Borrowed)) {
+  if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
     return false;
   }
 
@@ -4892,15 +4889,13 @@ static bool ParseModule(JSContext* cx, unsigned argc, Value* vp) {
   }
   options.setModule();
 
-  AutoStableStringChars stableChars(cx);
-  if (!stableChars.initTwoByte(cx, scriptContents)) {
+  AutoStableStringChars linearChars(cx);
+  if (!linearChars.initTwoByte(cx, scriptContents)) {
     return false;
   }
 
-  const char16_t* chars = stableChars.twoByteRange().begin().get();
   JS::SourceText<char16_t> srcBuf;
-  if (!srcBuf.init(cx, chars, scriptContents->length(),
-                   JS::SourceOwnership::Borrowed)) {
+  if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
     return false;
   }
 
@@ -8195,13 +8190,12 @@ static bool EntryPoints(JSContext* cx, unsigned argc, Value* vp) {
         return false;
       }
 
-      AutoStableStringChars stableChars(cx);
-      if (!stableChars.initTwoByte(cx, codeString)) {
+      AutoStableStringChars linearChars(cx);
+      if (!linearChars.initTwoByte(cx, codeString)) {
         return false;
       }
       JS::SourceText<char16_t> srcBuf;
-      if (!srcBuf.init(cx, stableChars.twoByteRange().begin().get(),
-                       codeString->length(), JS::SourceOwnership::Borrowed)) {
+      if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
         return false;
       }
 
diff --git a/js/src/vm/JSFunction.cpp b/js/src/vm/JSFunction.cpp
index a025a886016c..ab2f58a0b990 100644
--- a/js/src/vm/JSFunction.cpp
+++ b/js/src/vm/JSFunction.cpp
@@ -1675,17 +1675,13 @@ static bool CreateDynamicFunction(JSContext* cx, const CallArgs& args,
   }
 
   // Steps 7.a-b, 8.a-b, 9.a-b, 16-28.
-  AutoStableStringChars stableChars(cx);
-  if (!stableChars.initTwoByte(cx, functionText)) {
+  AutoStableStringChars linearChars(cx);
+  if (!linearChars.initTwoByte(cx, functionText)) {
     return false;
   }
 
-  mozilla::Range<const char16_t> chars = stableChars.twoByteRange();
-  SourceOwnership ownership = stableChars.maybeGiveOwnershipToCaller()
-                                  ? SourceOwnership::TakeOwnership
-                                  : SourceOwnership::Borrowed;
   SourceText<char16_t> srcBuf;
-  if (!srcBuf.init(cx, chars.begin().get(), chars.length(), ownership)) {
+  if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
     return false;
   }
 
diff --git a/js/src/wasm/AsmJS.cpp b/js/src/wasm/AsmJS.cpp
index d74de915718e..192528ed1d85 100644
--- a/js/src/wasm/AsmJS.cpp
+++ b/js/src/wasm/AsmJS.cpp
@@ -7009,18 +7009,13 @@ static bool HandleInstantiationFailure(JSContext* cx, CallArgs args,
     options.setForceStrictMode();
   }
 
-  AutoStableStringChars stableChars(cx);
-  if (!stableChars.initTwoByte(cx, src)) {
+  AutoStableStringChars linearChars(cx);
+  if (!linearChars.initTwoByte(cx, src)) {
     return false;
   }
 
   SourceText<char16_t> srcBuf;
-
-  const char16_t* chars = stableChars.twoByteRange().begin().get();
-  SourceOwnership ownership = stableChars.maybeGiveOwnershipToCaller()
-                                  ? SourceOwnership::TakeOwnership
-                                  : SourceOwnership::Borrowed;
-  if (!srcBuf.init(cx, chars, end - begin, ownership)) {
+  if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
     return false;
   }