Remove isUnclippedDescendant.

Remove isUnclippedDescendant.

It's no longer used for anything except a single layout test. The test still
has pixel results, and I believe the only reason it had been using
isUnclippedDescendant in the first place was to show that it was functioning
the same way as the legacy composited scrolling path in the same situation.

(The layout test was added here:
https://chromiumcodereview.appspot.com/22620002)

This patch will need a layout test rebaseline, because the pixel tests will
no longer have any text on them.

BUG=420742
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=184553

[hartmanng, 2014-10-28 21:29:28]

hartmanng@chromium.org changed reviewers:
+ vollick@chromium.org

[hartmanng, 2014-10-28 21:29:28]

Ian, please take a look.

[Ian Vollick, 2014-10-28 21:41:14]

On 2014/10/28 at 21:29:28, hartmanng wrote:
> Ian, please take a look.

lgtm - thank you for cleaning this up.

[Ian Vollick, 2014-10-28 21:43:17]

The CQ bit was checked by vollick@chromium.org

[commit-bot: I haz the power, 2014-10-28 21:44:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/686973002/20001

[hartmanng, 2014-10-28 23:48:50]

Oops, the related layout tests also used that script and will need rebaselining.
Trying again.

[hartmanng, 2014-10-28 23:48:54]

The CQ bit was checked by hartmanng@chromium.org

[commit-bot: I haz the power, 2014-10-28 23:49:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/686973002/40001

[commit-bot: I haz the power, 2014-10-29 00:50:38]

Committed patchset #3 (id:40001) as 184553