Fix file-watcher on mac by always starting/stopping through the run-loop thread.
Fix file-watcher on mac by always starting/stopping through the run-loop thread.

This also fixes some system error-printing and maybe also early events.

BUG=https://code.google.com/p/dart/issues/detail?id=16216
R=sgjesse@google.com

Review URL: https://codereview.chromium.org//147083015

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@32355 260f80e4-7a28-3924-810f-c04153c831b5

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