ignored performance test when not loading ruby-prof

Rails edge ignored ruby-prof when running with ruby-2.0.0 now. but test of performance test in railties is running and it always failed.

I ignored this test of performance test. if ruby-prof support ruby-2.0.0 and we added it to Gemfile. this test is enabled.

I think this problem is last fails of rails edge with ruby-2.0.0.