Restore trunk@6519, "Flipping DisclosurePanel arrow in RTL.", which didn't break anything at all. This reverts commit 102f96b9ee3c0d2e53fefe2e67876384efabd935. git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@6529 8db76d5a-ed1c-0410-87a9-c151d255dfc7