Fix WorkerGlobalScopePerformance thread state mismatch asserts.

Source/modules/performance/WorkerGlobalScopePerformance.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 WorkerGlobalScopePerformance_h
 #define WorkerGlobalScopePerformance_h
 
 #include "core/workers/WorkerSupplementable.h"
 #include "heap/Handle.h"
+#include "modules/performance/WorkerPerformance.h"
 
 namespace WebCore {
 
-class WorkerPerformance;
-
 class WorkerGlobalScopePerformance FINAL : public WorkerSupplement {
 public:
     virtual ~WorkerGlobalScopePerformance();
     static WorkerGlobalScopePerformance* from(WorkerGlobalScope*);
 
     static WorkerPerformance* performance(WorkerGlobalScope*);
 
 private:
     WorkerGlobalScopePerformance();
 
     WorkerPerformance* performance();
     static const char* supplementName();
 
     RefPtrWillBePersistent<WorkerPerformance> m_performance;
 };
 
 } // namespace WebCore
 
 #endif // WorkerGlobalScopePerformance_h