Make re-exported classes appear as if they are part of the original library.

Make re-exported classes appear as if they are part of the original library.

This is a WIP -- I need to finish the recursive updating of exported fields, but
everything else should be there.


BUG=
R=alanknight@google.com

Committed: https://code.google.com/p/dart/source/detail?r=30831

[Emily Fortuna, 2013-12-03 22:37:49]

This fixes the bulk of the issue. More cleanup and the recursive visiting to be
implemented shortly.

[Alan Knight, 2013-12-03 22:48:06]

lgtm

https://codereview.chromium.org/103083003/diff/20001/pkg/docgen/lib/docgen.dart
File pkg/docgen/lib/docgen.dart (right):

https://codereview.chromium.org/103083003/diff/20001/pkg/docgen/lib/docgen.da...
pkg/docgen/lib/docgen.dart:907: /// Returns a [ClassGroup] containing error,
typedef and regular classes.
If it's void now, comment should be updated.

https://codereview.chromium.org/103083003/diff/20001/pkg/docgen/lib/docgen.da...
pkg/docgen/lib/docgen.dart:1176: 
I know this is the rough version. Comments and types for these would be good for
the polished version.

[Emily Fortuna, 2013-12-03 23:05:33]

Committed patchset #1 manually as r30831 (presubmit successful).