Respect order dependencies in ImplicitConstructorBuilder.

Respect order dependencies in ImplicitConstructorBuilder.

Since implicit constructors for a mixin application are based on the
constructors of the superclass, we must build implicit constructors
for superclasses before we build them for derived classes.

BUG=dartbug.com/21600
R=brianwilkerson@google.com, scheglov@google.com

Committed: https://code.google.com/p/dart/source/detail?r=42052

[Paul Berry, 2014-12-01 21:30:07]

paulberry@google.com changed reviewers:
+ scheglov@google.com

[scheglov, 2014-12-01 21:41:20]

LGTM, but I'd like Brian to take a lot on it too.

[Paul Berry, 2014-12-01 21:42:06]

paulberry@google.com changed reviewers:
+ brianwilkerson@google.com

[Brian Wilkerson, 2014-12-01 22:08:55]

LGTM

[Paul Berry, 2014-12-01 22:35:49]

Committed patchset #2 (id:20001) manually as 42052 (presubmit successful).