Fixed a bug where IE would synthesize extra click events on a double click.

Patch by: jlabanca
Review by: jgw (desk)
Issue: 3392



git-svn-id: https://google-web-toolkit.googlecode.com/svn/releases/1.6@4910 8db76d5a-ed1c-0410-87a9-c151d255dfc7