dart2js source mirrors should either provide access to exports or include exported elements

[alan-knight]

In the context of docgen, we are using dart2js source mirrors to extract the documentation information. However, the library mirrors we receive do not include exported members, and as far as I can see there is no way to retrieve them. We can look them up by name if we already know the name, but there is no way to get the list of names. So a program of the form

library stuff;
import 'src/otherStuff.dart';
export 'src/otherStuff.dart';
<EOF>
then has no documentation.

[alan-knight]

Marked this as blocking #12759.

[kasperl]

Added this to the Later milestone.
Removed Priority-Unassigned, Area-Dart2Dart labels.
Added Priority-Medium, Area-Dart2JS, Triaged labels.

[kasperl]

Removed this from the Later milestone.
Added Oldschool-Milestone-Later label.

[kasperl]

Removed Oldschool-Milestone-Later label.

[sigmundch]

Now that dartdoc was moved away from the source-mirrors library and is using the analyzer parser directly, we will deprecate the source-mirrors library. So we are not planning to add this feature anymore.
@sigmundch