e314fc2671
Now handles negative width/height so that it's equivalent to
new Rectangle.fromPoints(new Point(left, top),
new Point(left + width, top + height))
BUG= http://dartbug.com/16167
R=efortuna@google.com
Review URL: https://codereview.chromium.org//135273009
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@32736 260f80e4-7a28-3924-810f-c04153c831b5