using browser detection in js_common (via ssi), have FF/Xulrunner load the postbody...

using browser detection in js_common (via ssi), have  FF/Xulrunner load the postbody JS loader and all other browsers load the regular js_common content, w/ some slight changes to keep inline JS out of the picture.  This is all because IE treats JS loaded vis legacyRequire as running in the non-global scope, which pretty much breaks all the code loaded in this fashion