Move static member function normalizeRange() out from VisibleSelection

Move static member function normalizeRange() out from VisibleSelection

This patch moves static member function |normalizeRange()| out from
|VisibleSelection| to "EditingUtilities.{cpp,h}" to make |VisibleSelection|
class not to use |PositionInComposedTree| directly for ease of templatazing
|VisibleSelection| to introduce composed tree version.

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=201538

[yosin_UTC9, 2015-09-01 07:47:33]

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

[yosin_UTC9, 2015-09-01 07:57:44]

PTAL

[hajimehoshi, 2015-09-01 08:14:51]

lgtm

[yosin_UTC9, 2015-09-01 08:15:18]

The CQ bit was checked by yosin@chromium.org

[commit-bot: I haz the power, 2015-09-01 08:15:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1328493002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1328493002/1

[commit-bot: I haz the power, 2015-09-01 08:48:45]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201538