Kill [SetWrapperReferenceFromReference] IDL extended attribute

Source/bindings/tests/idls/TestInterfacePython4.idl

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// This is for interface extended attributes that interact with another extended
-// attribute, and thus both cannot be tested at once.
-// The more *minor* extended attribute should be put in this file.
-
-[
-    SetWrapperReferenceFromReference=document,  // Conflicts with [SetWrapperReferenceTo], [SetWrapperReferenceFrom] and [Custom=VisitDOMWrapper]
-] interface TestInterfacePython4 {   
-};