Remaining Node to Element conversion in FocusController

Remaining Node to Element conversion in FocusController

- Converted Node*/Node& parameter to Element where possible
- Converted NodeTraversal to ElementTraversal where possible

There are still some places where Node/NodeTraversal are
used, but converting them to use Element made the code
less readable.

This is the last of Node to Element conversion for
FocusController.

BUG=499667
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197788

[kochi, 2015-06-24 10:29:19]

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

[commit-bot: I haz the power, 2015-06-24 10:29:41]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1200423004/1

[kochi, 2015-06-24 10:32:16]

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

[kochi, 2015-06-24 11:10:43]

PTAL

[commit-bot: I haz the power, 2015-06-24 11:28:04]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-24 11:28:05]

Dry run: This issue passed the CQ dry run.

[hayato, 2015-06-25 00:55:40]

lgtm

[kochi, 2015-06-25 00:59:58]

The CQ bit was checked by kochi@chromium.org

[commit-bot: I haz the power, 2015-06-25 01:00:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1200423004/1

[commit-bot: I haz the power, 2015-06-25 01:04:11]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197788