Move honorEditingBoundaryAtOr{Before,After}() out from VisiblePosition class

Move honorEditingBoundaryAtOr{Before,After}() out from VisiblePosition class

This patch moves |honorEditingBoundaryAtOr{Before,After}()| out from
|VisiblePosition| class to simplify |VisiblePosition| for introducing
composed tree version of |VisiblePosition|.

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=201467

[yosin_UTC9, 2015-08-31 05:46:09]

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

[yosin_UTC9, 2015-08-31 05:46:15]

PTAL

[hajimehoshi, 2015-08-31 06:16:23]

lgtm

[yosin_UTC9, 2015-08-31 06:16:49]

The CQ bit was checked by yosin@chromium.org

[commit-bot: I haz the power, 2015-08-31 06:16:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1313963003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1313963003/1

[commit-bot: I haz the power, 2015-08-31 06:40:11]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201467