Update from https://crrev.com/312600

sky/engine/bindings/core/v8/WindowProxy.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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 66 matching lines @@
     bool initialize();
 
     enum GlobalDetachmentBehavior {
         DoNotDetachGlobal,
         DetachGlobal
     };
     void disposeContext(GlobalDetachmentBehavior);
 
     // The JavaScript wrapper for the document object is cached on the global
     // object for fast access. UpdateDocumentProperty sets the wrapper
-    // for the current document on the global object. ClearDocumentProperty
-    // deletes the document wrapper from the global object.
+    // for the current document on the global object.
     void updateDocumentProperty();
-    void clearDocumentProperty();
 
     void createContext();
     bool installDOMWindow();
 
     static WindowProxy* enteredIsolatedWorldContext();
 
     LocalFrame* m_frame;
     v8::Isolate* m_isolate;
     RefPtr<ScriptState> m_scriptState;
     RefPtr<DOMWrapperWorld> m_world;
     ScopedPersistent<v8::Object> m_global;
     ScopedPersistent<v8::Object> m_document;
 };
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_BINDINGS_CORE_V8_WINDOWPROXY_H_