Add a thread-safety assertion in DEFINE_STATIC_LOCAL

Source/wtf/ThreadingWin.cpp

 /*
  * Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile, 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
@@ skipping 373 matching lines @@
     if (absoluteTime < currentTime)
         return 0;
 
     // Time is too far in the future (and would overflow unsigned long) - wait forever.
     if (absoluteTime - currentTime > static_cast<double>(INT_MAX) / 1000.0)
         return INFINITE;
 
     return static_cast<DWORD>((absoluteTime - currentTime) * 1000.0);
 }
 
+#if ENABLE(ASSERT)
+static bool s_threadCreated = false;
+
+struct ThreadCreationRecorder {
+    ThreadCreationRecorder()
+    {
+        ASSERT(!s_threadCreated);
+        s_threadCreated = true;
+    }
+};
+
+bool isAtomicallyInitializedStaticMutexLockHeld()
+{
+    return atomicallyInitializedStaticMutex && atomicallyInitializedStaticMutex->locked();
+}
+
+bool isBeforeThreadCreated()
+{
+    return !s_threadCreated;
+}
+
+void willCreateThread()
+{
+    static ThreadCreationRecorder recorder;
+}
+#endif
+
 } // namespace WTF
 
 #endif // OS(WIN)