Merge r3536 and r3538 to trunk to fix performance issue with

src/runtime.cc

 // Copyright 2006-2009 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 5391 matching lines @@
           Factory::DictionaryAtNumberPut(dict, index, elm);
       if (!result.is_identical_to(dict))
         storage_ = result;
     }
   }
 
   void increase_index_offset(uint32_t delta) {
     index_offset_ += delta;
   }
 
+  Handle<FixedArray> storage() { return storage_; }
+
  private:
   Handle<FixedArray> storage_;
   uint32_t index_limit_;
   bool fast_elements_;
   uint32_t index_offset_;
 };
 
 
 template<class ExternalArrayClass, class ElementType>
 static uint32_t IterateExternalArrayElements(Handle<JSObject> receiver,
@@ skipping 289 matching lines @@
                   Factory::NewNumberDictionary(at_least_space_for));
   }
 
   Handle<Object> len = Factory::NewNumber(static_cast<double>(result_length));
 
   ArrayConcatVisitor visitor(storage, result_length, fast_case);
 
   IterateArguments(arguments, &visitor);
 
   result->set_length(*len);
-  result->set_elements(*storage);
+  // Please note the storage might have changed in the visitor.
+  result->set_elements(*visitor.storage());
 
   return *result;
 }
 
 
 // This will not allocate (flatten the string), but it may run
 // very slowly for very deeply nested ConsStrings.  For debugging use only.
 static Object* Runtime_GlobalPrint(Arguments args) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 1);
@@ skipping 2310 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal