http://jsfiddle.net/dstorey/YwnsR/ (default time zone)
http://jsfiddle.net/dstorey/gLnvQ/ (UTC time zone, long name)
http://jsfiddle.net/dstorey/gLnvQ/1/ (UTC time zone, short name)
0. Load the URLs above in IE11
1. Open F12 console
2. Click Run
For first URL, in the console, it should show the hour and time zone name that you are currently in, using short representation.
I'm in Pacific Time, so in Chrome, it displays:
"4 PM PT " (it should probably be PDT as it is daylight savings time)
For http://jsfiddle.net/dstorey/gLnvQ/ it should show the hour and time zone using UTC, using long representation.
In Chrome it displays "12 AM GMT+00:00", but I suppose it could also use the full name of the time zone, such as "Coordinated Universal Time". I don't think the spec defines exactly where the values of the time zone name should be.
Only the hour is displayed in IE11:
"4 PM" (first link)
"12 PM" (second link)
* The timeZoneName property is being set correctly on the DateTimeFormat, so it is just not being used when formatting the string. This makes the formatted date/time ambiguous.
* This is less of an issue as in IE, you can only use the default time zone and UTC. Chrome allows you to to set any time zone (the spec says only "utc" and undefined are needed, but others can be implemented in certain situations).