Oilpan: move MessageChannel to the heap.

Source/bindings/v8/custom/V8MessageChannelCustom.cpp

Index: Source/bindings/v8/custom/V8MessageChannelCustom.cpp
diff --git a/Source/bindings/v8/custom/V8MessageChannelCustom.cpp b/Source/bindings/v8/custom/V8MessageChannelCustom.cpp
index d7ea6cee81f90c8355404dda60d0b647e32e33e1..d39c588710dca7ff67efb8feeb982d7792770b0b 100644
--- a/Source/bindings/v8/custom/V8MessageChannelCustom.cpp
+++ b/Source/bindings/v8/custom/V8MessageChannelCustom.cpp
@@ -44,7 +44,7 @@ void V8MessageChannel::constructorCustom(const v8::FunctionCallbackInfo<v8::Valu
 {
     ExecutionContext* context = currentExecutionContext(info.GetIsolate());
 
-    RefPtr<MessageChannel> obj = MessageChannel::create(context);
+    RefPtrWillBeRawPtr<MessageChannel> obj = MessageChannel::create(context);
 
     v8::Local<v8::Object> wrapper = info.Holder();