Revert of Make the CPDFXFA_App non-global

fxjs/fxjs_v8.h

 // 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
 
 // FXJS_V8 is a layer that makes it easier to define native objects in V8, but
 // has no knowledge of PDF-specific native objects. It could in theory be used
 // to implement other sets of native objects.
 
@@ skipping 121 matching lines @@
   explicit CFXJS_Engine(v8::Isolate* pIsolate);
   ~CFXJS_Engine();
 
   using Constructor = void (*)(CFXJS_Engine* pEngine,
                                v8::Local<v8::Object> obj);
   using Destructor = void (*)(CFXJS_Engine* pEngine, v8::Local<v8::Object> obj);
 
   static CFXJS_Engine* CurrentEngineFromIsolate(v8::Isolate* pIsolate);
   static int GetObjDefnID(v8::Local<v8::Object> pObj);
 
+#ifdef PDF_ENABLE_XFA
+  // Called as part of FXJS_InitializeEngine, exposed so PDF can make its
+  // own contexts compatible with XFA or vice versa.
+  static void SetForV8Context(v8::Local<v8::Context> v8Context,
+                              CFXJS_Engine* pEngine);
+#endif  // PDF_ENABLE_XFA
+
   v8::Isolate* GetIsolate() const { return m_isolate; }
 
   // Always returns a valid, newly-created objDefnID.
   int DefineObj(const wchar_t* sObjName,
                 FXJSOBJTYPE eObjType,
                 Constructor pConstructor,
                 Destructor pDestructor);
 
   void DefineObjMethod(int nObjDefnID,
                        const wchar_t* sMethodName,
@@ skipping 94 matching lines @@
   void SetIsolate(v8::Isolate* pIsolate) { m_isolate = pIsolate; }
 
  private:
   v8::Isolate* m_isolate;
   v8::Global<v8::Context> m_V8PersistentContext;
   std::vector<v8::Global<v8::Object>*> m_StaticObjects;
   std::map<CFX_WideString, v8::Global<v8::Array>> m_ConstArrays;
 };
 
 #endif  // FXJS_FXJS_V8_H_