Improves GWT event dispatch for extensibility.

New implementation introduces a dispatcher map for bitless events and
uses a 'default' dispatch function if there is no specific dispatcher
defined for the event.

Similarly, a dispatcher map for capture events introduced as well that
simplifies the boiler-plate around capture events.

With this change even if the event is not known by GWT yet, it will
still be dispatched. As most events don't need custom dispatching, no
further changes will be required to DOMImpl (e.g. MGWT will no longer
need to rebind DOMImpl for transitionEnd and animationEnd as those will
work out of the box.)

Partially fixes issue 8379

Change-Id: Ia00c177d0f007d544d4837e2291c991615795474
Review-Link: https://gwt-review.googlesource.com/#/c/5222/
2 files changed