Replace uses of v8::Persistent with ScopedPersistent.

third_party/WebKit/Source/bindings/core/v8/ScopedPersistent.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 54 matching lines @@
     {
         return v8::Local<T>::New(isolate, m_handle);
     }
 
     template<typename P>
     void setWeak(P* parameters, void (*callback)(const v8::WeakCallbackInfo<P>&), v8::WeakCallbackType type = v8::WeakCallbackType::kParameter)
     {
         m_handle.SetWeak(parameters, callback, type);
     }
 
+    // Turns this handle into a weak phantom handle without
+    // finalization callback.
+    void setPhantom()
+    {
+        m_handle.SetWeak();
+    }
+
     void clearWeak()
     {
         m_handle.template ClearWeak<void>();
     }
 
     bool isEmpty() const { return m_handle.IsEmpty(); }
     bool isWeak() const { return m_handle.IsWeak(); }
 
     void set(v8::Isolate* isolate, v8::Local<T> handle)
     {
@@ skipping 30 matching lines @@
     {
         return m_handle;
     }
 
     v8::Persistent<T> m_handle;
 };
 
 } // namespace blink
 
 #endif // ScopedPersistent_h