Fix JSON serialization of PerformanceEntry subclasses

third_party/WebKit/Source/core/timing/PerformanceEntry.cpp

 /*
  * Copyright (C) 2012 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 68 matching lines @@
     if (equalIgnoringCase(entryType, "render"))
         return Render;
     if (equalIgnoringCase(entryType, "resource"))
         return Resource;
     return Invalid;
 }
 
 ScriptValue PerformanceEntry::toJSONForBinding(ScriptState* scriptState) const
 {
     V8ObjectBuilder result(scriptState);
-    result.addString("name", name());
-    result.addString("entryType", entryType());
-    result.addNumber("startTime", startTime());
-    result.addNumber("duration", duration());
+    buildJSONValue(result);
     return result.scriptValue();
 }
 
+void PerformanceEntry::buildJSONValue(V8ObjectBuilder& builder) const
+{
+    builder.addString("name", name());
+    builder.addString("entryType", entryType());
+    builder.addNumber("startTime", startTime());
+    builder.addNumber("duration", duration());
+}
+
 } // namespace blink