Remove tests for playing video in reverse, which is not supported in Blink

These tests, being marked as [ Timeout ], do nothing but slow down test runs.

If this feature is ever implemented, it'll be easy to resurrect these tests,
as I'm attaching this patch to the feature bug.

R=ojan@chromium.org
BUG=33099

Review URL: https://codereview.chromium.org/16266005

git-svn-id: svn://svn.chromium.org/blink/trunk@151708 bbb929c8-8fbe-4397-9dbb-9b2b20218538
5 files changed