Add documentation for enyo.Scroller.getBounds describing the returned object in more detail.

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Quote 'volatile' used as bare word in ComputedPropertySupport
because it's a ES3 "future reserved word", and we need ES3
support for IE8.  Caught by jshint 2.1.6+.

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Merge pull request #362 from enyojs/scroller-getbounds-docs

Scroller getbounds docs