IDL: Add support for [TreatNullAs=EmptyString]

Source/bindings/core/v8/V8Binding.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 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 865 matching lines @@
         v8::Local<v8::Array> propertyNames = object->GetPropertyNames();
         uint32_t length = propertyNames->Length();
         for (uint32_t i = 0; i < length; i++) {
             v8::Local<v8::Value> name = propertyNames->Get(v8::Int32::New(isolate, i));
             // FIXME(yurys): v8::Object should support GetOwnPropertyNames
             if (name->IsString() && !object->HasRealNamedProperty(v8::Handle<v8::String>::Cast(name)))
                 continue;
             RefPtr<JSONValue> propertyValue = v8ToJSONValue(isolate, object->Get(name), maxDepth);
             if (!propertyValue)
                 return nullptr;
-            TOSTRING_DEFAULT(V8StringResource<WithNullCheck>, nameString, name, nullptr);
+            TOSTRING_DEFAULT(V8StringResource<TreatNullAsNullString>, nameString, name, nullptr);
             jsonObject->setValue(nameString, propertyValue);
         }
         return jsonObject;
     }
     ASSERT_NOT_REACHED();
     return nullptr;
 }
 
 V8TestingScope::V8TestingScope(v8::Isolate* isolate)
     : m_handleScope(isolate)
@@ skipping 35 matching lines @@
 PassRefPtr<TraceEvent::ConvertableToTraceFormat> devToolsTraceEventData(ExecutionContext* context, v8::Handle<v8::Function> function, v8::Isolate* isolate)
 {
     int scriptId = 0;
     String resourceName;
     int lineNumber = 1;
     GetDevToolsFunctionInfo(function, isolate, scriptId, resourceName, lineNumber);
     return InspectorFunctionCallEvent::data(context, scriptId, resourceName, lineNumber);
 }
 
 } // namespace WebCore