combine XML DOM creation code

[Adam Peller]

_base.xhr, dojo.io.frame, dojox.data.dom and dojox.xml.parser all implement logic to instantiate the IE ActiveX XMLDOM, which is brittle as it is. Combine the code. Also, consider deprecating dojox.data.dom.createDocument.

Consider using the code in the _base.query test for maximum reuse. It's really not that bad a kludge, on second thought.

			function createDocument(xml){
				var fauxXhr = { responseText: xml };
				if("DOMParser" in dojo.global){
					var parser = new DOMParser();
					fauxXhr.responseXML = parser.parseFromString(xml, "text/xml");
				}
				// kludge: use dojo.xhr contentHandler for XML to process IE XMLDOC as needed
				return dojo._contentHandlers["xml"](fauxXhr); // DOMDocument
			}

[Jared Jurkiewicz]

Initial patch that moves the dojox.data.dom functions to dojox.xml, and does some general cleanup on projects that used dojox.data.dom

[Jared Jurkiewicz]

(In [15961]) Minor update to localise lookup of XML parsers by using _base private function. refs #8140

[Adam Peller]

(In [15962]) Style changes. Refs #8140

[Adam Peller]

(In [15963]) Style changes. Refs #8140

[Adam Peller]

(In [15965]) unb0rk forEach loops from [15953]. Refs #8140

[Jared Jurkiewicz]

(In [15968]) Removed unused require related to xml. refs #8140

[Jared Jurkiewicz]

Going ahead and closing this as the code has been moved, tested, etc.