Oilpan: fix gcc compilation.

Source/platform/heap/ThreadState.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 525 matching lines @@
         ASSERT(!m_preFinalizers.contains(&target));
         ASSERT(!sweepForbidden());
         m_preFinalizers.add(&target, &T::invokePreFinalizer);
     }
 
     // Cancel above requests.  The argument should be |*this|.  This function is
     // ignored if it is called in pre-finalizer functions.
     template<typename T>
     void unregisterPreFinalizer(T& target)
     {
+        static_assert(sizeof(&T::invokePreFinalizer) > 0, "Declaration of USING_PRE_FINALIZER()'s prefinalizer trampoline not in scope.");
         checkThread();
-        ASSERT(&T::invokePreFinalizer);
         unregisterPreFinalizerInternal(&target);
     }
 
     Vector<PageMemoryRegion*>& allocatedRegionsSinceLastGC() { return m_allocatedRegionsSinceLastGC; }
 
     void shouldFlushHeapDoesNotContainCache() { m_shouldFlushHeapDoesNotContainCache = true; }
 
     void registerTraceDOMWrappers(v8::Isolate* isolate, void (*traceDOMWrappers)(v8::Isolate*, Visitor*))
     {
         m_isolate = isolate;
@@ skipping 198 matching lines @@
 };
 
 template<> class ThreadStateFor<AnyThread> {
 public:
     static ThreadState* state() { return ThreadState::current(); }
 };
 
 } // namespace blink
 
 #endif // ThreadState_h