Revert of perf: Disable browse:news:reddit on Mac

tools/perf/page_sets/system_health/browsing_stories.py

 # Copyright 2016 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.
 
 from page_sets.system_health import platforms
 from page_sets.system_health import system_health_story
 
 from page_sets.login_helpers import pinterest_login
 
 from telemetry import decorators
@@ skipping 148 matching lines @@
 
 # Desktop qq.com opens a news item in a separate tab, for which the back button
 # does not work.
 class QqMobileStory(_NewsBrowsingStory):
   NAME = 'browse:news:qq'
   URL = 'http://news.qq.com'
   ITEM_SELECTOR = '.list .full a'
   SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
 
 
-@decorators.Disabled('mac')  # crbug.com/662959
 class RedditDesktopStory(_NewsBrowsingStory):
   """The top website in http://www.alexa.com/topsites/category/News"""
   NAME = 'browse:news:reddit'
   URL = 'https://www.reddit.com/r/news/top/?sort=top&t=week'
   ITEM_SELECTOR = '.thing .title > a'
   SUPPORTED_PLATFORMS = platforms.DESKTOP_ONLY
 
 
 class RedditMobileStory(_NewsBrowsingStory):
   """The top website in http://www.alexa.com/topsites/category/News"""
@@ skipping 178 matching lines @@
       inner_save_function = 'document.querySelector(".nameAndIcons")'
       action_runner.WaitForElement(element_function=inner_save_function)
       action_runner.ClickElement(element_function=inner_save_function)
       action_runner.Wait(1)  # Wait to make navigation realistic.
 
     # Close selection.
     x_element_function = ('document.querySelector('
                           '".Button.borderless.close.visible")')
     action_runner.ClickElement(element_function=x_element_function)
     action_runner.Wait(1)  # Wait to make navigation realistic.