For issue 3048, make toggle buttons (and other custom buttons) have the
"aria-pressed" WAI-ARIA state when they get toggled.

patch by: ajr
review by: rdayal (desk review)



git-svn-id: https://google-web-toolkit.googlecode.com/svn/releases/1.6@4254 8db76d5a-ed1c-0410-87a9-c151d255dfc7