[co19] Roll co19 to b071a4729a57ee47dcc7330ab9ea3566ef58e5c2
[co19] Roll co19 to b071a4729a57ee47dcc7330ab9ea3566ef58e5c2

2020-06-10 sgrekhov@unipro.ru Mixin tests fixed (references to super are allowed, superclass other than Object not)
2020-06-09 sgrekhov@unipro.ru Fixes 726. Language\Mixins\Mixin_Application tests migrated to null safety
2020-06-09 irina.arkhipets@gmail.com Fixed issue 703: Missing Issue tags added.
2020-06-09 sgrekhov@unipro.ru Subtyping tests fixed to not to fail on tryjobs
2020-06-09 sgrekhov@unipro.ru Fixes 725. Language\Mixins tests migrated to null safety
2020-06-08 sgrekhov@unipro.ru Fixed errors or issue numbers added in the tests migrated to NNBD
2020-06-05 irina.arkhipets@gmail.com Fixed issue 607: Missing Issue tags added, tests corrected.
2020-06-05 sgrekhov@unipro.ru Fixed errors in the tests migrated to NNBD
2020-06-05 sgrekhov@unipro.ru Fixed numerous errors in the tests migrated to NNBD
2020-06-05 sgrekhov@unipro.ru Fixed numerous errors in the tests migrated to NNBD
2020-06-05 irina.arkhipets@gmail.com Missing Issue tag for 42196 added.
2020-06-05 irina.arkhipets@gmail.com Fixed Issue 646: Missing Issue tags for 36959, 37050 added, test corrected.
2020-06-05 irina.arkhipets@gmail.com Missing Issue tags for 36959, 37050 are added.
2020-06-05 irina.arkhipets@gmail.com Issue 723: Language\Libraries_and_Scripts\Exports tests adopted for nnbd.
2020-06-05 irina.arkhipets@gmail.com Issue 721: Language\Interfaces tests adopted for nnbd.
2020-06-04 sgrekhov@unipro.ru 478. Expected result fixed

Change-Id: I5ffe7f6272c5906643eda81364a2cfcec48ba042
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150743
Reviewed-by: William Hesse <a821cddceae7dc400f272e3cb1a72f400f9fed6d@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk