22766 Manual roll of Dart SDK from ce76503f5b46 to dcd5a8f005a (cla: yes)

22768 Roll Dart SDK from dcd5a8f005a2 to 960620d2e811 (794 revisions) (cla: yes, waiting for tree to go green)

22769 Cleanup dart_runner examples & tests. (cla: yes, waiting for tree to go green)

22770 add file package to deps in prep for glob update (cla: yes, waiting for tree to go green)

22771 [web] Add new line break type (prohibited) (cla: yes, platform-web)