Upstream change to also kill fletch as part of task_kill.py.
Upstream change to also kill fletch as part of task_kill.py.

This is to keep the patching of our branch as small as possible (and to guarantee consistency if we share bots between sdk and fletch runners)

R=ahe@google.com, whesse@google.com
BUG=

Review URL: https://codereview.chromium.org//1304613002 .

dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk