Mark http/tests/notifications/close-dispatch-asynchronous.html Slow
Mark http/tests/notifications/close-dispatch-asynchronous.html Slow

Mark the http/tests/notifications/close-dispatch-asynchronous.html test
as SLOW as it has been timing out taking 6 seconds (just over the 5 sec
limit) 29 out of the last 200 runs.

TBR=pdr@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/1206933002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@197762 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