Cutover v8 to use new style callbacks internally

src/extensions/gc-extension.h

Index: src/extensions/gc-extension.h
diff --git a/src/extensions/gc-extension.h b/src/extensions/gc-extension.h
index 54b865adf75335d42ac12415cea19f5f72cbca20..e412b92a4d997aad87160ddd789b85419bdf3037 100644
--- a/src/extensions/gc-extension.h
+++ b/src/extensions/gc-extension.h
@@ -38,7 +38,7 @@ class GCExtension : public v8::Extension {
   explicit GCExtension(const char* source) : v8::Extension("v8/gc", source) {}
   virtual v8::Handle<v8::FunctionTemplate> GetNativeFunction(
       v8::Handle<v8::String> name);
-  static v8::Handle<v8::Value> GC(const v8::Arguments& args);
+  static void GC(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Register();
 };