[co19] Roll co19 to bbba568b780a48c69a1de8ad1a8527a37cf71fad

2020-07-07 sgrekhov@unipro.ru Fixes 786. LibTest\async\Zone migrated to null safety
2020-07-07 sgrekhov@unipro.ru More leftFutureOr tests added and also generator migrated to null safety
2020-07-06 sgrekhov@unipro.ru Debug output removed and issue number added
2020-07-06 sgrekhov@unipro.ru Language/Statements tests fixed after tryjob run
2020-07-06 sgrekhov@unipro.ru Fixes 784. LibTest\async\Timer migrated to null safety
2020-07-06 sgrekhov@unipro.ru Fixes 783. LibTest\async\StreamTransformer migrated to null safety
2020-07-06 sgrekhov@unipro.ru Fixes 782. LibTest\async\StreamIterator migrated to null safety
2020-07-03 sgrekhov@unipro.ru Fixes 780. StreamConsumer, StreamController and StreamSink tests migrated to null safety
2020-07-03 sgrekhov@unipro.ru Make getter and setter to have the same type
2020-07-02 sgrekhov@unipro.ru Return an expected type from the test

Change-Id: I746333ddb8505f62041da8ec4a80ba223cfe5594
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153353
Reviewed-by: William Hesse <whesse@google.com>

DEPS

@@ -44,7 +44,7 @@ vars = {
   # co19 is a cipd package. Use update.sh in tests/co19[_2] to update these
   # hashes. It requires access to the dart-build-access group, which EngProd
   # has.
-  "co19_rev": "4035c66f0cacb70064395473cb54d810c046c225",
+  "co19_rev": "bbba568b780a48c69a1de8ad1a8527a37cf71fad",
   "co19_2_rev": "620c1148c8b7a3d7f74afacf348c46f109eb64f2",
 
   # The internal benchmarks to use. See go/dart-benchmarks-internal