Introduce isRenderedCharacter(Position) function

Introduce isRenderedCharacter(Position) function

This patch introduces |isRenderedCharacter(Position)()| as replacement of
|PositionAlgorithm<Strategy>::isRenderedCharacter()| to simplify source code
for improving code health, since |isRenderedCharacter()| is used only for
positions in DOM tree, thus we don't need to have composed tree version.

This patch is a part of |Position| class cleanup to reduce |LayoutObject|
dependency.


BUG=518738
TEST=n/a; no behavior changes

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200801

[yosin_UTC9, 2015-08-19 04:03:08]

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

[yosin_UTC9, 2015-08-19 04:03:15]

PTAL

[hajimehoshi, 2015-08-19 04:29:40]

lgtm

[yosin_UTC9, 2015-08-19 04:39:21]

The CQ bit was checked by yosin@chromium.org

[commit-bot: I haz the power, 2015-08-19 04:39:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1286993006/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1286993006/1

[commit-bot: I haz the power, 2015-08-19 06:11:17]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200801