Bug 1017030 - Part 3: Replace AutoPushJSContext in PostMessageRunnable::Run. r=bholley

dom/base/MessagePort.cpp

@@ -13,6 +13,7 @@
 #include "nsContentUtils.h"
 #include "nsGlobalWindow.h"
 #include "nsPresContext.h"
+#include "ScriptSettings.h"
 
 #include "nsIDocument.h"
 #include "nsIDOMFile.h"
@@ -271,14 +272,14 @@ PostMessageRunnable::Run()
 {
   MOZ_ASSERT(mPort);
 
-  // Get the JSContext for the target window
-  nsCOMPtr<nsIScriptGlobalObject> sgo = do_QueryInterface(mPort->GetOwner());
-  NS_ENSURE_STATE(sgo);
-  nsCOMPtr<nsIScriptContext> scriptContext = sgo->GetContext();
-  AutoPushJSContext cx(scriptContext ? scriptContext->GetNativeContext()
-                                     : nsContentUtils::GetSafeJSContext());
+  nsCOMPtr<nsIGlobalObject> globalObject = do_QueryInterface(mPort->GetOwner());
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_UNEXPECTED;
+  }
 
-  MOZ_ASSERT(cx);
+  AutoJSAPI jsapi;
+  JSContext* cx = jsapi.cx();
+  JSAutoCompartment ac(cx, globalObject->GetGlobalJSObject());
 
   // Deserialize the structured clone data
   JS::Rooted<JS::Value> messageData(cx);