Rebase the Dart Generator test files for 2014.

The test files include the year 2013 in the heading, and causes test
failures when a 2014 generated file is tested.

NOTRY=true

Review URL: https://codereview.chromium.org/134463006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244525 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244525