Add LineScanner and SpanScanner classes to string_scanner.

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//299973002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/string_scanner@36815 260f80e4-7a28-3924-810f-c04153c831b5
14 files changed
tree: 70a502e6c79bd170a35597db4d408c2b519567d2
  1. pkgs/