Add testRunner.runIdleTasks() to force idle tasks to run.

components/scheduler/scheduler.gyp

 # Copyright 2015 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.
 
 {
   'variables': {
     # This turns on e.g. the filename-based detection of which
     # platforms to include source files on (e.g. files ending in
     # _mac.h or _mac.cc are only compiled on MacOSX).
     'chromium_code': 1,
@@ skipping 36 matching lines @@
         '<@(scheduler_sources)',
       ],
       'export_dependent_settings': [
         '../../third_party/WebKit/public/blink.gyp:blink',
       ],
     },
     {
       # GN version: //components/scheduler:test_support
       'target_name': 'scheduler_test_support',
       'type': 'static_library',
+      'dependencies': [
+        '../../third_party/WebKit/public/blink.gyp:blink',
+      ],
       'include_dirs': [
         '../..',
       ],
       'sources': [
         '<@(scheduler_test_support_sources)',
       ],
     },
   ],
 }