Skip stack trace formatting in case the global object is already dead.

src/handles.h

 // Copyright 2011 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 260 matching lines @@
 // Computes the enumerable keys from interceptors. Used for debug mirrors and
 // by GetKeysInFixedArrayFor below.
 v8::Handle<v8::Array> GetKeysForNamedInterceptor(Handle<JSReceiver> receiver,
                                                  Handle<JSObject> object);
 v8::Handle<v8::Array> GetKeysForIndexedInterceptor(Handle<JSReceiver> receiver,
                                                    Handle<JSObject> object);
 
 enum KeyCollectionType { LOCAL_ONLY, INCLUDE_PROTOS };
 
 // Computes the enumerable keys for a JSObject. Used for implementing
-// "for (n in object) { }".
+// "for (n in object) { }".  The side-effect free version omits getting keys
+// if it would trigger side effects.
+template<bool allow_side_effect>
 Handle<FixedArray> GetKeysInFixedArrayFor(Handle<JSReceiver> object,
                                           KeyCollectionType type,
                                           bool* threw);
-Handle<JSArray> GetKeysFor(Handle<JSReceiver> object, bool* threw);
 Handle<FixedArray> ReduceFixedArrayTo(Handle<FixedArray> array, int length);
 Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object,
                                        bool cache_result);
 
 // Computes the union of keys and return the result.
 // Used for implementing "for (n in object) { }"
 Handle<FixedArray> UnionOfKeys(Handle<FixedArray> first,
                                Handle<FixedArray> second);
 
 Handle<String> SubString(Handle<String> str,
@@ skipping 39 matching lines @@
   inline ~NoHandleAllocation();
  private:
   int level_;
   bool active_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_H_