Make assertion scopes thread safe.

src/deoptimizer.h

 // Copyright 2012 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 431 matching lines @@
   // Number of output frames.
   int output_count_;
   // Number of output js frames.
   int jsframe_count_;
   // Array of output frame descriptions.
   FrameDescription** output_;
 
   List<Object*> deferred_arguments_objects_values_;
   List<ArgumentsObjectMaterializationDescriptor> deferred_arguments_objects_;
   List<HeapNumberMaterializationDescriptor> deferred_heap_numbers_;
+#ifdef DEBUG
+  DisallowHeapAllocation* disallow_heap_allocation_;
+#endif  // DEBUG
 
   bool trace_;
 
   static const int table_entry_size_;
 
   friend class FrameDescription;
   friend class DeoptimizingCodeListNode;
   friend class DeoptimizedFrameInfo;
 };
 
@@ skipping 479 matching lines @@
   Object** expression_stack_;
   int source_position_;
 
   friend class Deoptimizer;
 };
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_DEOPTIMIZER_H_