Add the refresh action back to the Editor's file view.

R=scheglov@google.com

Review URL: https://codereview.chromium.org//676063002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41290 260f80e4-7a28-3924-810f-c04153c831b5
add enum support prefs to experimental pref page

BUG=dartbug.com/21414
R=jwren@google.com

Review URL: https://codereview.chromium.org//673303002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41291 260f80e4-7a28-3924-810f-c04153c831b5