Minor tweaks to speed up vxJS.dom.parse(), vxJS.event.addListener() considers an Event object provided as argument in the MS-DOM branch, too; global.event is kept as fallback.
Minor tweaks to speed up vxJS.dom.parse(), vxJS.event.addListener()
considers an Event object provided as argument in the MS-DOM branch,
too; global.event is kept as fallback.

Change-Id: Icbb41c4424a9e3f42f912ea719d2f86ff173ecfc

Vectrex/vxJS