Fix WorkerGlobalScopePerformance thread state mismatch asserts.

Source/modules/performance/WorkerPerformance.h

 /*
  * Copyright (C) 2013 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 15 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WorkerPerformance_h
 #define WorkerPerformance_h
 
 #include "bindings/v8/ScriptWrappable.h"
 #include "core/dom/ContextLifecycleObserver.h"
+#include "heap/Handle.h"
+#include "heap/ThreadState.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 
 namespace WebCore {
 
 class ExecutionContext;
 
 class WorkerPerformance : public RefCountedWillBeGarbageCollectedFinalized<WorkerPerformance>, public ScriptWrappable {
     DECLARE_GC_INFO;
 public:
     static PassRefPtrWillBeRawPtr<WorkerPerformance> create() { return adoptRefWillBeNoop(new WorkerPerformance()); }
     ~WorkerPerformance();
 
     double now(ExecutionContext*) const;
 
     void trace(Visitor*) { }
 
 private:
     WorkerPerformance();
 };
 
+USED_FROM_MULTIPLE_THREADS(WorkerPerformance);
+
 }
 
 #endif // WorkerPerformance_h