Remove flaky line for fast/line-grid/line-align-left-edges.html.

It no longer times out on Linux.

BUG=313659
TBR=yurys@chromium.org

Review URL: https://codereview.chromium.org/130463002

git-svn-id: svn://svn.chromium.org/blink/trunk@164750 bbb929c8-8fbe-4397-9dbb-9b2b20218538