Marquee: Early-exit on negative duration as well as zero duration

It is possible for HTMLMarqueeElement::GetAnimationParameters to return
a negative duration - this occurs when the <marquee> has no size but its
'mover' does. In this case we should not attempt to animate as this will
just throw in TimingInput::Update (as a negative duration is invalid).

Bug: 866289
Change-Id: Ifa0c2d2e8c717284670f7bddf8d350c174094f57
Reviewed-on: https://chromium-review.googlesource.com/1148887
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Stephen McGruer <smcgruer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577894}
3 files changed