Reenable Flipboard story on Mac

BUG=662021, 663025
TBR=perejzu@chromium.org

Review-Url: https://codereview.chromium.org/2602073002
Cr-Commit-Position: refs/heads/master@{#440974}

tools/perf/benchmarks/system_health_smoke_test.py

@@ -32,8 +32,6 @@ def GetSystemHealthBenchmarksToSmokeTest():
 
 
 _DISABLED_TESTS = frozenset({
-  # crbug.com/662021
-  'benchmarks.system_health_smoke_test.SystemHealthBenchmarkSmokeTest.system_health.memory_desktop.browse:news:flipboard',  # pylint: disable=line-too-long
   # crbug.com/629123
   'benchmarks.system_health_smoke_test.SystemHealthBenchmarkSmokeTest.system_health.memory_mobile.browse:news:hackernews',  # pylint: disable=line-too-long
   'benchmarks.system_health_smoke_test.SystemHealthBenchmarkSmokeTest.system_health.memory_mobile.browse:news:nytimes',  # pylint: disable=line-too-long

tools/perf/page_sets/system_health/browsing_stories.py

@@ -129,7 +129,6 @@ class FlipboardMobileStory(_NewsBrowsingStory):
     return possible_browser.platform.IsSvelte()  # crbug.com/668097
 
 
-@decorators.Disabled('mac') # crbug.com/663025
 class FlipboardDesktopStory(_NewsBrowsingStory):
   NAME = 'browse:news:flipboard'
   URL = 'https://flipboard.com/explore'