Fix two issues with modular compilation in dartk.

Fix two issues with modular compilation in dartk.

- The interface for a factory constructor in an external library would
  reference the class type parameters instead of its own.

- When a class from an external library gets promoted to mixin level,
  the rest of the library should not be considered "being loaded".
  This would cause members to not get added to the AST.

BUG=
R=kmillikin@google.com

Committed: https://github.com/dart-lang/sdk/commit/2f331ecd1b0da7df535b6314c5249fef40916370

[asgerf, 2017-02-22 15:21:17]

asgerf@google.com changed reviewers:
+ kmillikin@google.com

[Kevin Millikin (Google), 2017-02-23 11:09:36]

lgtm

[asgerf, 2017-02-23 11:38:26]

Description was changed from

==========
Fix two issues with modular compilation in dartk.

- The interface for a factory constructor in an external library would
  reference the class type parameters instead of its own.

- When a class from an external library gets promoted to mixin level,
  the rest of the library should not be considered "being loaded".
  This would cause members to not get added to the AST.

BUG=
==========

to

==========
Fix two issues with modular compilation in dartk.

- The interface for a factory constructor in an external library would
  reference the class type parameters instead of its own.

- When a class from an external library gets promoted to mixin level,
  the rest of the library should not be considered "being loaded".
  This would cause members to not get added to the AST.

BUG=
R=kmillikin@google.com

Committed:
https://github.com/dart-lang/sdk/commit/2f331ecd1b0da7df535b6314c5249fef40916370
==========

[asgerf, 2017-02-23 11:38:27]

Committed patchset #4 (id:60001) manually as
2f331ecd1b0da7df535b6314c5249fef40916370 (presubmit successful).