Invalidate cross-thread persistents on heap termination.

Source/platform/heap/ThreadState.h

Index: Source/platform/heap/ThreadState.h
diff --git a/Source/platform/heap/ThreadState.h b/Source/platform/heap/ThreadState.h
index c098f13abb01baaeb028f556f20bbfca355640a8..0c015aeee37db03a46d4f7c03e250cddb3e39ba8 100644
--- a/Source/platform/heap/ThreadState.h
+++ b/Source/platform/heap/ThreadState.h
@@ -544,7 +544,6 @@ public:
     void threadLocalWeakProcessing();
 
     size_t objectPayloadSizeForTesting();
-    void prepareHeapForTermination();
 
     // Register the pre-finalizer for the |self| object. This method is normally
     // called in the constructor of the |self| object. The class T must have
@@ -705,6 +704,8 @@ private:
     void cleanup();
     void cleanupPages();
 
+    void prepareForThreadStateTermination();
+
     void invokePreFinalizers();
 
     void takeSnapshot(SnapshotType);