Remove backpointer to CJS_Runtime from CJS_Value

fpdfsdk/javascript/JS_Object.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "fpdfsdk/javascript/JS_Object.h"
 
 #include "fpdfsdk/include/fsdk_mgr.h"
 #include "fpdfsdk/javascript/JS_Define.h"
 #include "fpdfsdk/javascript/cjs_context.h"
 
 CJS_EmbedObj::CJS_EmbedObj(CJS_Object* pJSObject) : m_pJSObject(pJSObject) {}
 
 CJS_EmbedObj::~CJS_EmbedObj() {
-  m_pJSObject = nullptr;
 }
 
 void FreeObject(const v8::WeakCallbackInfo<CJS_Object>& data) {
   CJS_Object* pJSObj = data.GetParameter();
   pJSObj->ExitInstance();
   delete pJSObj;
   FXJS_FreePrivate(data.GetInternalField(0));
 }
 
 void DisposeObject(const v8::WeakCallbackInfo<CJS_Object>& data) {
@@ skipping 14 matching lines @@
                       v8::WeakCallbackType::kInternalFields);
 }
 
 void CJS_Object::Dispose() {
   m_pV8Object.Reset();
 }
 
 void CJS_Object::InitInstance(IJS_Runtime* pIRuntime) {}
 
 void CJS_Object::ExitInstance() {}