Some more removals of dart:utf.
Some more removals of dart:utf.

R=jmesserly@google.com, lrn@google.com, nweiz@google.com

Review URL: https://codereview.chromium.org//22909059

git-svn-id: b90127a0f73590c96be848d3e4cb640efa9a7657@26712 260f80e4-7a28-3924-810f-c04153c831b5

dart-archive/scheduled_test,dart-lang/scheduled_test