Exit Transition not executed if no Enter Transition is specified

[cata]

Please see http://try.websharper.com/snippet/0000Da This is broken in both WS 3 and WS 4

See also #120 for a project you can use to repro locally in WS 4:

• Comment out all but one transition attributes (to work arounf #120)
• Verify that transitions work
• Now, comment out the call to Transition.Enter - exit transition is not performed.

[cata]

Re-tested this with Zafir.UI.Next 4.0.150.54-beta7 - still an issue.