Add just enough state changes from EXTERNAL (outside V8) to OTHER...

src/handles.cc

Index: src/handles.cc
===================================================================
--- src/handles.cc	(revision 1641)
+++ src/handles.cc	(working copy)
@@ -308,6 +308,11 @@
 // associated with the wrapper and get rid of both the wrapper and the
 // handle.
 static void ClearWrapperCache(Persistent<v8::Value> handle, void*) {
+#ifdef ENABLE_HEAP_PROTECTION
+  // Weak reference callbacks are called as if from outside V8.  We
+  // need to reeenter to unprotect the heap.
+  VMState state(OTHER);
+#endif
   Handle<Object> cache = Utils::OpenHandle(*handle);
   JSValue* wrapper = JSValue::cast(*cache);
   Proxy* proxy = Script::cast(wrapper->value())->wrapper();