Set up isolate in CFXJS_Engine's constructor

fxjs/fxjs_v8_embeddertest.cpp

 // Copyright 2015 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.
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/js_embedder_test.h"
 
 namespace {
 
 const double kExpected0 = 6.0;
@@ skipping 27 matching lines @@
   v8::Context::Scope context_scope(GetV8Context());
 
   ExecuteInCurrentContext(CFX_WideString(kScript1));
   CheckAssignmentInCurrentContext(kExpected1);
 }
 
 TEST_F(FXJSV8EmbedderTest, MultipleEngines) {
   v8::Isolate::Scope isolate_scope(isolate());
   v8::HandleScope handle_scope(isolate());
 
-  CFXJS_Engine engine1;
-  engine1.SetIsolate(isolate());
+  CFXJS_Engine engine1(isolate());
   engine1.InitializeEngine();
 
-  CFXJS_Engine engine2;
-  engine2.SetIsolate(isolate());
+  CFXJS_Engine engine2(isolate());
   engine2.InitializeEngine();
 
   v8::Context::Scope context_scope(GetV8Context());
   ExecuteInCurrentContext(CFX_WideString(kScript0));
   CheckAssignmentInCurrentContext(kExpected0);
 
   {
     v8::Local<v8::Context> context1 = engine1.NewLocalContext();
     v8::Context::Scope context_scope1(context1);
     ExecuteInCurrentContext(CFX_WideString(kScript1));
     CheckAssignmentInCurrentContext(kExpected1);
   }
 
   engine1.ReleaseEngine();
 
   {
     v8::Local<v8::Context> context2 = engine2.NewLocalContext();
     v8::Context::Scope context_scope2(context2);
     ExecuteInCurrentContext(CFX_WideString(kScript2));
     CheckAssignmentInCurrentContext(kExpected2);
   }
 
   engine2.ReleaseEngine();
   CheckAssignmentInCurrentContext(kExpected0);
 }