XHR IFrame Proxy Tests

Run this test from a web server, not from local disk.

DEPRECATED: dojo/io/iframe Use dojo/request/iframe. -- will be removed in version: 2.0
DEPRECATED: dojox.data.dom Use dojox.xml.parser instead. -- will be removed in version: 2.0
DEPRECATED: dojo.moduleUrl() use require.toUrl -- will be removed in version: 2.0