Add support for the new "unix" editing behavior.
Add support for the new "unix" editing behavior.

BUG=none
TEST=none; the layout test that will use this will come soon.


Review URL: http://codereview.chromium.org/4886003

git-svn-id: http://src.chromium.org/svn/trunk/src@65957 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: b6d29117b59258767465dfbe9ec0607a77a1b9e5
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser