[co19] Roll co19 to 373869fb6ab96191868589e73a13711c31690402

2020-09-03 [email protected] Some LanguageFeatures and Utils tests fixed
2020-09-03 [email protected] Fixes 929. Make devVal of CreateStreamWithErrorsFunction to be required

Change-Id: I3ea5781ac9c51fbe34c34dad7d95c6642c0da90b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/161707
Reviewed-by: Alexander Thomas <[email protected]>

Author: whesse

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": "9c07e26d67665de7972ba6f7e87369933a978545",
+  "co19_rev": "373869fb6ab96191868589e73a13711c31690402",
   "co19_2_rev": "e48b3090826cf40b8037648f19d211e8eab1b4b6",
 
   # The internal benchmarks to use. See go/dart-benchmarks-internal