[runtime] Speed up Object::ToObject with JSReceiver argument.

src/objects-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 1125 matching lines @@
   } else if (FLAG_track_heap_object_fields && representation.IsHeapObject()) {
     return IsHeapObject();
   }
   return true;
 }
 
 
 // static
 MaybeHandle<JSReceiver> Object::ToObject(Isolate* isolate,
                                          Handle<Object> object) {
-  return ToObject(
-      isolate, object, handle(isolate->context()->native_context(), isolate));
+  if (object->IsJSReceiver()) return Handle<JSReceiver>::cast(object);
+  return ToObject(isolate, object, isolate->native_context());
 }
 
 
 // static
 MaybeHandle<Object> Object::ToPrimitive(Handle<Object> input,
                                         ToPrimitiveHint hint) {
   if (input->IsPrimitive()) return input;
   return JSReceiver::ToPrimitive(Handle<JSReceiver>::cast(input), hint);
 }
 
@@ skipping 6686 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_