Issue 21559. Increase console buffer size to 1000000 characters.

R=brianwilkerson@google.com
BUG= https://code.google.com/p/dart/issues/detail?id=21559

Review URL: https://codereview.chromium.org//723433002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41691 260f80e4-7a28-3924-810f-c04153c831b5
Revert "Emit warning on import of dart:mirrors."

This reverts commit r41688.

Review URL: https://codereview.chromium.org//717103004

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41692 260f80e4-7a28-3924-810f-c04153c831b5