Move highestAncestorOrSelf() from Node to NodeTraversal

Move highestAncestorOrSelf() from Node to NodeTraversal

Move highestAncestorOrSelf() from Node to NodeTraversal as this is a DOM
traversal utility function.

This CL also simplifies the method implementation.

R=adamk@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=179263

[adamk, 2014-07-30 21:09:14]

lgtm

the const qualifier on the old method was pretty bogus :)

[Inactive, 2014-07-30 21:10:21]

The CQ bit was checked by ch.dumez@samsung.com

[commit-bot: I haz the power, 2014-07-30 21:11:32]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/ch.dumez@samsung.com/425383002/1

[commit-bot: I haz the power, 2014-07-30 21:46:09]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/19726)

[commit-bot: I haz the power, 2014-07-30 22:39:21]

Change committed as 179263