Allow super calls in mixins (for now behind a --supermixin flag).

Allow super calls in mixins (for now behind a --supermixin flag).
As a consequence, allow a mixin application alias as a mixin, even if it does
not extend Object.
Add new tests.
Fix an existing test.
Update status files.

Fixes #23771

R=hausner@google.com

Committed: https://github.com/dart-lang/sdk/commit/15de03e2d5e91a11a955ac25405ea00a1d825216

[regis, 2015-07-17 00:13:48]

regis@google.com changed reviewers:
+ hausner@google.com

[regis, 2015-07-17 00:13:48]

With my deepest sympathies.

[hausner, 2015-07-17 16:55:22]

The sympathies should go to you, suffering the implementation of this insanity.

LGTM, with a G having the double meaning Good and Greek.

I presume the runtime flag is necessary so that some old tests don't fail. (The
problem with flags is that someone might complain about a breaking change when
you remove it again.)

https://codereview.chromium.org/1232613005/diff/1/tests/language/mixin_super_...
File tests/language/mixin_super_bound_test.dart (right):

https://codereview.chromium.org/1232613005/diff/1/tests/language/mixin_super_...
tests/language/mixin_super_bound_test.dart:23: class MNA<U, V, W> extends
S<List<U>> with M<V, U>, N<List<W>, List<W>> { }
A short comment would be helpful, explaining what the expected errors are in
checked mode.

[regis, 2015-07-17 18:29:51]

Thanks!

The runtime flag is part of the strategy to bring this feature online (see
#23770 for details). Note that the flag is still false by default. It is true
that some tests will need to be cleaned up or removed once we flip the flag
default.

https://codereview.chromium.org/1232613005/diff/1/tests/language/mixin_super_...
File tests/language/mixin_super_bound_test.dart (right):

https://codereview.chromium.org/1232613005/diff/1/tests/language/mixin_super_...
tests/language/mixin_super_bound_test.dart:23: class MNA<U, V, W> extends
S<List<U>> with M<V, U>, N<List<W>, List<W>> { }
On 2015/07/17 16:55:22, hausner wrote:
> A short comment would be helpful, explaining what the expected errors are in
> checked mode.

Done here and in the other test.

[regis, 2015-07-17 18:32:27]

Committed patchset #2 (id:20001) manually as
15de03e2d5e91a11a955ac25405ea00a1d825216 (presubmit successful).