lib/utf: remove codepointsToString
lib/utf: remove codepointsToString

point folks to use String.fromCharCodes

Review URL: https://codereview.chromium.org//13493020

git-svn-id: cc4dd9cb38464c4587d28ee9e76805c5809f114b@21151 260f80e4-7a28-3924-810f-c04153c831b5

dart-lang/source_maps