Remove Timeout expectation for test following Blink/Chromium fix.

Blink and Chromium changes landed, immediate improvement to timeouts
shown on the flakiness dashboard. Calling it good.

BUG=226256
NOTRY=true
TBR=alecflett@chromium.org

Review URL: https://chromiumcodereview.appspot.com/21053005

git-svn-id: svn://svn.chromium.org/blink/trunk@155090 bbb929c8-8fbe-4397-9dbb-9b2b20218538