+1  A: 

Possibly not one of the answers you expected, but as a long-time Java professional I would go with Google Web Toolkit. Java in, compressed, obfuscated, optimized JavaScript out. And I can debug it in a Java debugger.

Carl Smotricz
It's only a matter of time before this is closed... 1 vote to go.
KP
Thanks Carl,Your answer is very relevant to what I asked for! Very cool hint.
green-i