Use intrinsics for builtin ArrayBuffer property accesses

src/runtime.cc

 // 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 934 matching lines @@
       v8::ArrayBufferView::kInternalFieldCount);
   for (int i = 0; i < v8::ArrayBufferView::kInternalFieldCount; i++) {
     holder->SetInternalField(i, Smi::FromInt(0));
   }
 
   ExternalArrayType array_type = kExternalInt8Array;  // Bogus initialization.
   size_t element_size = 1;  // Bogus initialization.
   Runtime::ArrayIdToTypeAndSize(arrayId, &array_type, &element_size);
 
   Handle<JSArrayBuffer> buffer = isolate->factory()->NewJSArrayBuffer();
+  if (source->IsJSTypedArray() &&
+      JSTypedArray::cast(*source)->type() == array_type) {
+    length_obj = Handle<Object>(JSTypedArray::cast(*source)->length(), isolate);
+  }
   size_t length = NumberToSize(isolate, *length_obj);
 
   if ((length > static_cast<unsigned>(Smi::kMaxValue)) ||
       (length > (kMaxInt / element_size))) {
     return isolate->Throw(*isolate->factory()->
           NewRangeError("invalid_typed_array_length",
             HandleVector<Object>(NULL, 0)));
   }
   size_t byte_length = length * element_size;
 
@@ skipping 14006 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal