IDL: Drop value conversion (V8 -> C++) macros from generated code

Source/bindings/core/v8/V8StringResource.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 161 matching lines @@
         : m_mode(Externalize)
     {
     }
 
     V8StringResource(v8::Handle<v8::Value> object)
         : m_v8Object(object)
         , m_mode(Externalize)
     {
     }
 
-    void operator=(v8::Handle<v8::Value> object)
+    V8StringResource& operator=(v8::Handle<v8::Value> object)
     {
         m_v8Object = object;
+        return *this;
     }
 
-    void operator=(const String& string)
+    V8StringResource& operator=(const String& string)
     {
         setString(string);
+        return *this;
     }
 
     void operator=(std::nullptr_t)
     {
         setString(String());
     }
 
     bool prepare()
     {
         if (prepareFast())
@@ skipping 108 matching lines @@
 }
 
 template<> inline String V8StringResource<TreatNullAndUndefinedAsNullString>::fallbackString() const
 {
     return String();
 }
 
 } // namespace blink
 
 #endif // V8StringResource_h