Specialize mint shift code on ia32 for a constant shift amount.

R=srdjan@google.com

Review URL: https://codereview.chromium.org//387733002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@38141 260f80e4-7a28-3924-810f-c04153c831b5
5 files changed