Add SpanScanner.location.

Also explicitly expose FileSpans and FileLocations.

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//683323002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/string_scanner@41383 260f80e4-7a28-3924-810f-c04153c831b5
3 files changed
tree: 202914a9fbbf8a57a2d3599bf96a0282f8bd260a
  1. pkgs/