Fixes Issue #1309.
Adds method DOM.eventGetCurrentEvent() to provide classes using the old
listener style interface a means to access the currently active event.

Patch by: jlabanca
Review by: jgw, knorton



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@1280 8db76d5a-ed1c-0410-87a9-c151d255dfc7