Bug 1297472 - Improve nsIScriptTimeoutHandler::GetHandlerText(), r=bz

dom/base/nsGlobalWindow.cpp

@@ -12218,8 +12218,7 @@ nsGlobalWindow::RunTimeoutHandler(nsTimeout* aTimeout,
   RefPtr<Function> callback = handler->GetCallback();
   if (!callback) {
     // Evaluate the timeout expression.
-    nsAutoString script;
-    handler->GetHandlerText(script);
+    const nsAString& script = handler->GetHandlerText();
 
     const char* filename = nullptr;
     uint32_t lineNo = 0, dummyColumn = 0;

dom/base/nsIScriptTimeoutHandler.h

@@ -34,7 +34,7 @@ public:
   virtual mozilla::dom::Function *GetCallback() = 0;
 
   // Get the handler text of not a compiled object.
-  virtual void GetHandlerText(nsAString& aString) = 0;
+  virtual const nsAString& GetHandlerText() = 0;
 
   // Get the location of the script.
   // Note: The memory pointed to by aFileName is owned by the

dom/base/nsJSTimeoutHandler.cpp

@@ -50,7 +50,7 @@ public:
   nsJSScriptTimeoutHandler(JSContext* aCx, WorkerPrivate* aWorkerPrivate,
                            const nsAString& aExpression);
 
-  virtual void GetHandlerText(nsAString& aString) override;
+  virtual const nsAString& GetHandlerText() override;
   virtual Function* GetCallback() override
   {
     return mFunction;
@@ -308,11 +308,11 @@ nsJSScriptTimeoutHandler::ReleaseJSObjects()
   }
 }
 
-void
-nsJSScriptTimeoutHandler::GetHandlerText(nsAString& aString)
+const nsAString&
+nsJSScriptTimeoutHandler::GetHandlerText()
 {
   NS_ASSERTION(!mFunction, "No expression, so no handler text!");
-  aString = mExpr;
+  return mExpr;
 }
 
 already_AddRefed<nsIScriptTimeoutHandler>

dom/workers/WorkerPrivate.cpp

@@ -5920,8 +5920,7 @@ WorkerPrivate::RunExpiredTimeouts(JSContext* aCx)
       AutoEntryScript aes(global, reason, false);
 
       // Evaluate the timeout expression.
-      nsAutoString script;
-      info->mHandler->GetHandlerText(script);
+      const nsAString& script = info->mHandler->GetHandlerText();
 
       const char* filename = nullptr;
       uint32_t lineNo = 0, dummyColumn = 0;
@@ -5932,7 +5931,7 @@ WorkerPrivate::RunExpiredTimeouts(JSContext* aCx)
 
       JS::Rooted<JS::Value> unused(aes.cx());
 
-      if (!JS::Evaluate(aes.cx(), options, script.get(),
+      if (!JS::Evaluate(aes.cx(), options, script.BeginReading(),
                         script.Length(), &unused) &&
           !JS_IsExceptionPending(aCx)) {
         retval = false;