Fix comment to correctly reflect octal value.

The actual value is correct: see nodejs/node-v0.x-archive#1999

Review URL: http://codereview.chromium.org//8747025

git-svn-id: http://dart.googlecode.com/svn/branches/bleeding_edge/dart@1946 260f80e4-7a28-3924-810f-c04153c831b5