Add a thread-safety assertion in DEFINE_STATIC_LOCAL

Source/wtf/ThreadingPthreads.cpp

 /*
  * Copyright (C) 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com)
  * Copyright (C) 2011 Research In Motion Limited. 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 228 matching lines @@
     int result = pthread_cond_signal(&m_condition);
     ASSERT_UNUSED(result, !result);
 }
 
 void ThreadCondition::broadcast()
 {
     int result = pthread_cond_broadcast(&m_condition);
     ASSERT_UNUSED(result, !result);
 }
 
+#if ENABLE(ASSERT)
+static bool s_threadCreated = false;
+
+struct ThreadCreationRecorder {
+    ThreadCreationRecorder()
+    {
+        ASSERT(!s_threadCreated);

[eroman, 2015/01/30 18:02:30]

Not sure how valuable this assertion is. Probably sufficient to just assign
s_threadCreated = true unconditionally as part of willCreateThread.

[kinuko, 2015/02/03 06:57:34]

Done.

+        s_threadCreated = true;
+    }
+};
+
+bool isAtomicallyInitializedStaticMutexLockHeld()
+{
+    return atomicallyInitializedStaticMutex && atomicallyInitializedStaticMutex->locked();
+}
+
+bool isBeforeThreadCreated()
+{
+    return !s_threadCreated;
+}
+
+void willCreateThread()
+{
+    static ThreadCreationRecorder recorder;
+}
+#endif
+
 } // namespace WTF
 
 #endif // USE(PTHREADS)