CustomElement: Use parentNode.removeChild(this) rather than domConstruct.destroy().
DialogUnderlay.js: Use native methods rather than dojo/dom*.
Likewise for winUtils.get().
 focus.js simplifications and reduction in dependence on dojo core.

1. Get rid of focus.curNode/prevNode; can just use document.activeElement.
2. Change API to see new widget stack from watch() to on().
3. Use native methods rather than dom.byId(), domAttr.get(), winUtils.get().
FormValueWidget.js: remove unused dependency.
FormWidget.js: use native methods rather than dojo/dom-style.
HasDropDown.js: remove unused dependencies.
place.js: use native methods rather than dojo/dom-style.
popup.js: use native methods rather than dojo/dom*, except for dom-geometry.position()
uacss.js simplifications

1. Remove setting of box-model CSS class.  This code existed in Dojo V1 mainly for IE
    running in quirks mode.  In modern browsers, everything is content-box model,
    unless you set CSS to override that.  But the CSS for border-box sizing can
    be set on any node, not just <html> or <body>, so I'm not sure it makes sense to
    try and detect it.

 2. Remove code for checking if document is in RTL mode.  I think this can be done through direct
     CSS, i.e. "[dir=rtl]".
Widget.js: use native methods rather than dojo/dom*.