[binding] Migrate XSLTProcessor.idl away from using custom V8 binding.

Source/bindings/core/v8/custom/custom.gypi

 # 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.
 
 {
     'variables': {
         'bindings_core_v8_custom_files': [
             'V8BlobCustom.cpp',
             'V8BlobCustomHelpers.cpp',
             'V8BlobCustomHelpers.h',
@@ skipping 22 matching lines @@
             'V8LocationCustom.cpp',
             'V8MessageChannelCustom.cpp',
             'V8MessageEventCustom.cpp',
             'V8MessagePortCustom.cpp',
             'V8MutationObserverCustom.cpp',
             'V8PopStateEventCustom.cpp',
             'V8WindowCustom.cpp',
             'V8WorkerCustom.cpp',
             'V8WorkerGlobalScopeCustom.cpp',
             'V8XMLHttpRequestCustom.cpp',
-            'V8XSLTProcessorCustom.cpp',
         ],
     },
 }