Oilpan: have Console be on the heap by default.

Source/core/workers/WorkerGlobalScope.h

Index: Source/core/workers/WorkerGlobalScope.h
diff --git a/Source/core/workers/WorkerGlobalScope.h b/Source/core/workers/WorkerGlobalScope.h
index 9a228c7438c35484a4732895f4bfe8030fd56433..71726e8033ea5c0db7833c28e043a0e688207f37 100644
--- a/Source/core/workers/WorkerGlobalScope.h
+++ b/Source/core/workers/WorkerGlobalScope.h
@@ -170,7 +170,7 @@ private:
     String m_userAgent;
     V8CacheOptions m_v8CacheOptions;
 
-    mutable RefPtrWillBeMember<WorkerConsole> m_console;
+    mutable PersistentWillBeMember<WorkerConsole> m_console;
     mutable PersistentWillBeMember<WorkerLocation> m_location;
     mutable PersistentWillBeMember<WorkerNavigator> m_navigator;