Update CHANGELOG.md for polymer before releasing it.
TBR=jakemac@google.com

Review URL: https://codereview.chromium.org//722783002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41694 260f80e4-7a28-3924-810f-c04153c831b5
Revert "Suppress canonicalization of Unbox() instruction that can deoptimize."

This reverts commit r41693 due to checked mode test failures.

TBR=fschneider@google.com
BUG=

Review URL: https://codereview.chromium.org//722793002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41695 260f80e4-7a28-3924-810f-c04153c831b5
Move unused local variables and classes analysis into HintGenerator.

R=brianwilkerson@google.com
BUG=

Review URL: https://codereview.chromium.org//719223002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41696 260f80e4-7a28-3924-810f-c04153c831b5