22195 Update painting.dart with an annotation error. (cla: yes, waiting for tree to go green)

22197 Roll Fuchsia Linux SDK from PY5hNI-wY… to Usec4YBzR… (cla: yes, waiting for tree to go green)

22198 Migrate runZoned to runZonedGuarded (cla: yes, waiting for tree to go green)

22203 Fix some serious lifecycle bugs with Android embedding code (cla: yes, platform-android, waiting for tree to go green)

22205 makes android semanticsnode to ignore hittest if it is not focusable (cla: yes, platform-android, waiting for tree to go green)

22213 Manual Roll of Dart to ba80ed989cc…9c6e76468ca (cla: yes, waiting for tree to go green)