make input type="search" RTL direction aware.

Swap the positions of cancel button and search icon if dir="rtl".

BUG=232333

Review URL: https://codereview.chromium.org/27323002

git-svn-id: svn://svn.chromium.org/blink/trunk@160706 bbb929c8-8fbe-4397-9dbb-9b2b20218538