Mark paint/masks/fieldset-mask.html slow on Win10
Mark paint/masks/fieldset-mask.html slow on Win10

BUG=529345
TBR=pdr@chromium.org

Review URL: https://codereview.chromium.org/1330033003 .

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@201919 bbb929c8-8fbe-4397-9dbb-9b2b20218538

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk