GTK: Fix tab strip width calculation for RTL
GTK: Fix tab strip width calculation for RTL

BUG=34763
TEST=see bug

Review URL: http://codereview.chromium.org/579006

git-svn-id: http://src.chromium.org/svn/trunk/src@38258 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 2816ef2ad4c1d60c4578689757d772603a5ca04e
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