Use EphemeralRange in makeSearchRange in VisibleSelection.cpp instead of Range object

Use EphemeralRange in makeSearchRange in VisibleSelection.cpp instead of Range object

This patch makes |makeSearchRange()| to use |EphemeralRange| instead of
|Range| object to avoid registering temporary |Range| object into |Document|
for Oilpan friendly and as a preparation of introducing full version of
|VisibleSelectionTemplate|.

This patch is a preparation of making selection to handle granularity for web
component, http://crrev.com/1363873004

BUG=388681, 513568
TEST=n/a; no behavior changes

Committed: https://crrev.com/4db8310fbdd01d9ef25cace80dbfab8350847796
Cr-Commit-Position: refs/heads/master@{#351045}

[yosin_UTC9, 2015-09-28 06:41:16]

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

[yosin_UTC9, 2015-09-28 06:41:17]

PTAL

[yoichio, 2015-09-28 07:14:42]

lgtm

[yosin_UTC9, 2015-09-28 07:29:33]

The CQ bit was checked by yosin@chromium.org

[commit-bot: I haz the power, 2015-09-28 07:29:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1375453002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1375453002/1

[commit-bot: I haz the power, 2015-09-28 09:37:04]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-28 09:38:27]

Patchset 1 (id:??) landed as
https://crrev.com/4db8310fbdd01d9ef25cace80dbfab8350847796
Cr-Commit-Position: refs/heads/master@{#351045}