Simplify UserAgentShadowRoot check for /deep/ selectors.

Simplify UserAgentShadowRoot check for /deep/ selectors.

User agent shadow roots cannot nest author shadow roots, so there's no
reason to check the type as we ascend every ancestor. Instead we can
just check the starting element in the checker.

R=timloh@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196286

[esprehn, 2015-06-02 03:51:39]

esprehn@chromium.org changed reviewers:
+ hayato@chromium.org

[esprehn, 2015-06-02 03:53:43]

The CQ bit was checked by esprehn@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-02 03:54:00]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1143003008/1

[hayato, 2015-06-02 04:20:54]

LGTM.

Note that I think we need to bring this change back when we are introducing a
(author) closed shadow tree.

[esprehn, 2015-06-02 04:30:15]

On 2015/06/02 at 04:20:54, hayato wrote:
> LGTM.
> 
> Note that I think we need to bring this change back when we are introducing a
(author) closed shadow tree.

We might, hopefully we'll have /deep/ sorted and maybe changed to work
differently for the static profile then.

[esprehn, 2015-06-02 04:30:18]

The CQ bit was unchecked by esprehn@chromium.org

[esprehn, 2015-06-02 04:30:24]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2015-06-02 04:30:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1143003008/1

[commit-bot: I haz the power, 2015-06-02 05:21:18]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196286