Move a member function intersectsNode() out from VisibleSelection class

Move a member function intersectsNode() out from VisibleSelection class

This patch moves a member function |intersectsNode()| out from
|VisibleSelection| class as a preparation of templatizing |VisibleSelection|
for introducing composed tree version of |VisibleSelection|.

This patch is a preparation of making selection to handle granularity for web
component, http://crrev.com/1277863002

BUG=513568
TEST=n/a; No behavior changes

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201304

[yosin_UTC9, 2015-08-27 09:13:58]

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

[yosin_UTC9, 2015-08-27 09:14:05]

PTAL

[hajimehoshi, 2015-08-27 09:16:36]

lgtm

[yosin_UTC9, 2015-08-27 09:18:38]

The CQ bit was checked by yosin@chromium.org

[commit-bot: I haz the power, 2015-08-27 09:18:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1316303002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1316303002/1

[commit-bot: I haz the power, 2015-08-27 10:27:54]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201304