Switch blink to use a gin-managed isolate.

Source/bindings/core/v8/V8Initializer.h

 /*
  * Copyright (C) 2009 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 14 matching lines @@
 
 #ifndef V8Initializer_h
 #define V8Initializer_h
 
 #include <v8.h>
 
 namespace blink {
 
 class V8Initializer {
 public:
-    static void initializeMainThreadIfNeeded(v8::Isolate*);
+    static void initializeMainThreadIfNeeded();
     static void initializeWorker(v8::Isolate*);
 };
 
 } // namespace blink
 
 #endif // V8Initializer_h