Remove flaky timeout expectation from compositing/geometry/video-fixed-scrolling.html

It passes consistently now.

BUG=245545
TBR=noel@chromium.org

Review URL: https://codereview.chromium.org/19598002

git-svn-id: svn://svn.chromium.org/blink/trunk@154414 bbb929c8-8fbe-4397-9dbb-9b2b20218538