Use ScopedTaskEnvironment instead of MessageLoop in tests that use v8.

mojo/edk/js/tests/BUILD.gn

 # 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.
 
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
 
 # TODO(hansmuller): The organization of tests in this directory is weird:
 #   * Really, js_unittests tests public stuff, so that should live in public
 #     and be reworked as some sort of apptest.
 #   * Both js_unittests and js_integration_tests should auto-generate their
 #     tests somehow. The .cc files are just test runner stubs, including
 #     explicit lists of .js files.
 
 group("tests") {
   testonly = true
   deps = [
     ":mojo_js_integration_tests",
     ":mojo_js_unittests",
   ]
 }
 
 test("mojo_js_integration_tests") {
   deps = [
     ":js_to_cpp_bindings",
+    "//base/test:test_support",
     "//gin:gin_test",
     "//mojo/common",
     "//mojo/edk/js",
     "//mojo/edk/test:run_all_unittests",
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/system",
     "//mojo/public/js:bindings",
   ]
 
   sources = [
@@ skipping 24 matching lines @@
     "//mojo/public/interfaces/bindings/tests:test_associated_interfaces",
     "//mojo/public/interfaces/bindings/tests:test_interfaces",
     "//mojo/public/js:tests",
   ]
 
   sources = [
     "//mojo/edk/js/handle_unittest.cc",
     "run_js_unittests.cc",
   ]
 }