Use timer task runner for V8PerIsolate tasks

gin/shell/gin_main.cc

 // Copyright 2013 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.
 
 #include "base/at_exit.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/files/file_util.h"
 #include "base/i18n/icu_util.h"
@@ skipping 62 matching lines @@
 #endif
 
   base::MessageLoop message_loop;
 
   // Initialize the base::FeatureList since IsolateHolder can depend on it.
   base::FeatureList::SetInstance(base::WrapUnique(new base::FeatureList));
 
   gin::IsolateHolder::Initialize(gin::IsolateHolder::kStrictMode,
                                  gin::IsolateHolder::kStableV8Extras,
                                  gin::ArrayBufferAllocator::SharedInstance());
-  gin::IsolateHolder instance;
-
+  gin::IsolateHolder instance(base::ThreadTaskRunnerHandle::Get());
 
   gin::GinShellRunnerDelegate delegate;
   gin::ShellRunner runner(&delegate, instance.isolate());
 
   {
     gin::Runner::Scope scope(&runner);
     runner.GetContextHolder()
         ->isolate()
         ->SetCaptureStackTraceForUncaughtExceptions(true);
   }
 
   base::CommandLine::StringVector args =
       base::CommandLine::ForCurrentProcess()->GetArgs();
   for (base::CommandLine::StringVector::const_iterator it = args.begin();
        it != args.end(); ++it) {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE,
         base::Bind(gin::Run, runner.GetWeakPtr(), base::FilePath(*it)));
   }
 
   base::RunLoop().RunUntilIdle();
   return 0;
 }