[cfe] Infer missing type arguments on enum elements

This CL also moves the resolution of the _Enum type before it's
checked for being a correct supertype.

Part of https://github.com/dart-lang/sdk/issues/47453

Change-Id: I80d4197a430b90e4aea785961bfbcbbee588255a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/228644
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Chloe Stefantsova <cstefantsova@google.com>

https://dart.googlesource.com/sdk/+/a03eb19a61dc9a60bb82bf5b23490e7bdab934a3
diff --git a/commits.json b/commits.json
index 35747b0..35f1f19 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
   "external/github.com/flutter/engine":"2ebc3d3e442d5b70d5755fdfa19787af8d2c645b",
   "external/github.com/flutter/flutter":"8017883a5dfd13d709c4bd04d617f54a6cb2271f",
-  "sdk":"26d9cb5146e7553ab7cc6d696e425793506b511f"
+  "sdk":"a03eb19a61dc9a60bb82bf5b23490e7bdab934a3"
 }
\ No newline at end of file