Fixes the firing of focus by FocusImplSafari. Calls to element.focus and
element.blur are unreliable in an event handler, so the impl now makes
the calls from within a setTimeout. This also has the side-effect of
fixing mouse-initiated keyboard navigation in CustomButtons.

Patch by: bobv, scottb
Review by: knorton



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@1176 8db76d5a-ed1c-0410-87a9-c151d255dfc7