ef7456f199
This reduces time of dart2js analysis after rename form 16000 ms to about 1200 ms, i.e. about 13 times ;-) R=brianwilkerson@google.com BUG= Review URL: https://codereview.chromium.org//844493005 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@42933 260f80e4-7a28-3924-810f-c04153c831b5