Bug fix: toPositionInComposedTree should treat positions with shadow roots

Bug fix: toPositionInComposedTree should treat positions with shadow roots

A PositionInComposedTree's anchor should not be a shadow root because
there should not be shadow roots in the composed tree world (similar to
crrev.com/1205023003). This CL fixes toPositionInComposedTree for a case
when a given position's anchor is a shadow root.

BUG=n/a
TEST=webkit_unit_tests --gtest_filter=PositionTest.*

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197815

[hajimehoshi, 2015-06-25 09:19:11]

hajimehoshi@chromium.org changed reviewers:
+ tkent@chromium.org, yosin@chromium.org

[hajimehoshi, 2015-06-25 09:19:11]

PTAL

[yosin_UTC9, 2015-06-25 09:33:06]

lgtm
Thanks!

[hajimehoshi, 2015-06-25 09:33:16]

The CQ bit was checked by hajimehoshi@chromium.org

[hajimehoshi, 2015-06-25 09:33:32]

The CQ bit was unchecked by hajimehoshi@chromium.org

[tkent, 2015-06-25 09:47:57]

lgtm

[hajimehoshi, 2015-06-25 10:26:08]

The CQ bit was checked by hajimehoshi@chromium.org

[commit-bot: I haz the power, 2015-06-25 10:26:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1204203002/20001

[commit-bot: I haz the power, 2015-06-25 11:50:08]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197815