Looking at their highly optimized code on google.com, my guess is that they already use all the tricks that work on _every_ browser. And it might not make much

Looking at their highly optimized code on google.com, my guess is that they already use all the tricks that work on _every_ browser. And it might not make much sense for them to have two builds: one elegant, with multiple files per page for newer browsers, and ugly optimized blob for older ones.