Make label.checkbox and label.radio use 'relative' position.
Make label.checkbox and label.radio use 'relative' position.

This makes absolute-positioned checkbox/radio input align with their outer
label element. If we don't do that, webkit might pick a wrong parent element
and not moving checkbox/radio element properly as in http://crosbug.com/7541.

BUG=chromium-os:7541
TEST=Verify fix for chromium-os:7541

Review URL: http://codereview.chromium.org/4100002

git-svn-id: http://src.chromium.org/svn/trunk/src@63938 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: e2accfa83ee2aa56df58bbe5650b8258bf8b5ce1
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