Add an additional optional argument to SpanScanner.spanFrom.

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//795343003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/string_scanner@42305 260f80e4-7a28-3924-810f-c04153c831b5
3 files changed
tree: 9888917618e4f0d0dacdb22525e0fc8937096f7b
  1. pkgs/