Stop suppressing generation of bindings with Promise. Add some tests for DOM APIs that answer promises.

R=vsm@google.com

Review URL: https://codereview.chromium.org//605853003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41136 260f80e4-7a28-3924-810f-c04153c831b5