Fix typemask bug.

* Enforce normalization of typemasks
* Improves message on assertion failure

BUG=
R=floitsch@google.com

Review URL: https://codereview.chromium.org//662513006

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41222 260f80e4-7a28-3924-810f-c04153c831b5
VM: Avoid repeated deoptimizations from hoisted array bounds checks.

R=vegorov@google.com

Review URL: https://codereview.chromium.org//662543003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41223 260f80e4-7a28-3924-810f-c04153c831b5
dart2js: Don't use 'init' as a marker for existing fields in makeConstantList.

R=kasperl@google.com

Review URL: https://codereview.chromium.org//660293003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41224 260f80e4-7a28-3924-810f-c04153c831b5
dart2js: Use `Array` as marker value for constant lists in the new emitter.

R=kasperl@google.com

Review URL: https://codereview.chromium.org//667683003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41225 260f80e4-7a28-3924-810f-c04153c831b5