Make EventHandler to use VisibleSelection::toNormalizedEphemeralRange() instead of toNormalizedRange

Make EventHandler to use VisibleSelection::toNormalizedEphemeralRange() instead of toNormalizedRange()

This patch changes |EventHandler| class to use |toNormalizedEphemeralRange()|
in |VisibleSelection| class instead of |toNormalizedRange()| as a preparation
of templatizing |VisibleSelection| to use templatized positions instead of
DOM position to represent range.

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=201121

[yosin_UTC9, 2015-08-25 08:56:30]

yosin@chromium.org changed reviewers:
+ tkent@chromium.org

[yosin_UTC9, 2015-08-25 08:56:40]

PTAL

[tkent, 2015-08-25 09:12:59]

lgtm

[yosin_UTC9, 2015-08-25 09:20:21]

The CQ bit was checked by yosin@chromium.org

[commit-bot: I haz the power, 2015-08-25 09:20:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1311623004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1311623004/1

[commit-bot: I haz the power, 2015-08-25 10:34:46]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201121