Fix TSAN issue wrt assertions in the optimizing compiler thread.

src/handles-inl.h

 // Copyright 2006-2008 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 34 matching lines @@
 
 
 template<typename T>
 Handle<T>::Handle(T* obj, Isolate* isolate) {
   ASSERT(!obj->IsFailure());
   location_ = HandleScope::CreateHandle(isolate, obj);
 }
 
 
 template <typename T>
-inline bool Handle<T>::is_identical_to(const Handle<T> other) const {
+inline bool Handle<T>::is_identical_to(const Handle<T> o) const {
   ASSERT(location_ == NULL || !(*location_)->IsFailure());
-  if (location_ == other.location_) return true;
-  if (location_ == NULL || other.location_ == NULL) return false;
   // Dereferencing deferred handles to check object equality is safe.
-  SLOW_ASSERT(IsDereferenceAllowed(NO_DEFERRED_CHECK) &&
-              other.IsDereferenceAllowed(NO_DEFERRED_CHECK));
-  return *location_ == *other.location_;
+  SLOW_ASSERT(
+      (location_ == NULL || IsDereferenceAllowed(NO_DEFERRED_CHECK)) &&
+      (o.location_ == NULL || o.IsDereferenceAllowed(NO_DEFERRED_CHECK)));
+  if (location_ == o.location_) return true;
+  if (location_ == NULL || o.location_ == NULL) return false;
+  return *location_ == *o.location_;
 }
 
 
 template <typename T>
 inline T* Handle<T>::operator*() const {
   ASSERT(location_ != NULL && !(*location_)->IsFailure());
   SLOW_ASSERT(IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK));
   return *BitCast<T**>(location_);
 }
 
@@ skipping 128 matching lines @@
   current->level = level_;
   ASSERT_EQ(current->next, current->limit);
   current->limit = limit_;
 }
 
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_INL_H_