Keeps recompile.js fresh at all times.

Changes from a static GET Foo.recompile.nocache.js to a dynamic GET of 
/recompile-requester/Foo to make sure that the recompile requester Js
is always fresh.

Previously the Js was always 1 version behind the compiled code, which 
led to compile failures when binding properties were mismatched.

Bug: issue 8996
Change-Id: I7e6cfc9cf5648460690a444bb7f87eaece234f51
Review-Link: https://gwt-review.googlesource.com/#/c/10212/