Force Mac editing behavior for fast/multicol/hit-test-above-or-below.html

Force Mac editing behavior for fast/multicol/hit-test-above-or-below.html

This way we won't need platform specific expectations, since it should now just
pass on all platforms. What to hit when you start selecting below the end of
the last column (or simply below the block in non-multicol), is
platform-specific. On Windows you hit the character that's directly above the
cursor, while on Linux and Mac you hit the end of the text.

This is another preparatory patch for enabling region based columns.

R=jchaffraix@chromium.org
BUG=334335
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192632

[eae, 2015-03-26 21:08:46]

eae@chromium.org changed reviewers:
+ eae@chromium.org

[eae, 2015-03-26 21:08:47]

LGTM

[mstensho (USE GERRIT), 2015-03-26 21:17:34]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2015-03-26 21:17:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1016603006/1

[commit-bot: I haz the power, 2015-03-26 22:33:02]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=192632