Correctly keep track of isolates for microtask execution

Source/core/dom/Microtask.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 22 matching lines @@
 
 #include "bindings/core/v8/V8PerIsolateData.h"
 #include "bindings/core/v8/V8RecursionScope.h"
 #include "platform/ScriptForbiddenScope.h"
 #include "platform/Task.h"
 #include "public/platform/WebThread.h"
 #include <v8.h>
 
 namespace blink {
 
-void Microtask::performCheckpoint()
+void Microtask::performCheckpoint(v8::Isolate* isolate)
 {
-    v8::Isolate* isolate = v8::Isolate::GetCurrent();
     V8PerIsolateData* isolateData = V8PerIsolateData::from(isolate);
     ASSERT(isolateData);
     if (isolateData->recursionLevel() || isolateData->performingMicrotaskCheckpoint() || isolateData->destructionPending() || ScriptForbiddenScope::isScriptForbidden())
         return;
     isolateData->setPerformingMicrotaskCheckpoint(true);
     {
         // Ensure that end-of-task-or-microtask actions are performed.
         V8RecursionScope recursionScope(isolate);
         isolate->RunMicrotasks();
     }
@@ skipping 16 matching lines @@
     v8::Isolate* isolate = v8::Isolate::GetCurrent();
     isolate->EnqueueMicrotask(&microtaskFunctionCallback, callback.leakPtr());
 }
 
 void Microtask::enqueueMicrotask(PassOwnPtr<Closure> callback)
 {
     enqueueMicrotask(adoptPtr(new Task(callback)));
 }
 
 } // namespace blink