Compiler used to compress the size before it's actually compressed in transmission. No reason to send "here-is-the-table-id-we-want-for-the-form" when you can just send "t-f-4"---the browser obviously doesn't care.

I'd assume that they are using http://code.google.com/closure/compiler/ on their JavaScript.

Odds are it's output from GWT, the same Java framework Google writes most of their apps in.