fix #355 button widget not focusable

In IE8+ the Button widget is not focusable because of the onfocusin method
used as an hack in <IE8
Closes #357
fix #365 skin inherited by the Bridge

closes #368
fix #369 - AT Debug Tools not working on IE7/8

Regression introduced in 1.2.4
closes #370

Conflicts:
	test/aria/core/CoreTestSuite.js
patch 1.2.7C