fix #27766, allow implicit casts from dynamic to composite types

pkg/analyzer/test/src/task/strong/checker_test.dart

Index: pkg/analyzer/test/src/task/strong/checker_test.dart
diff --git a/pkg/analyzer/test/src/task/strong/checker_test.dart b/pkg/analyzer/test/src/task/strong/checker_test.dart
index 48e6539e12d23711f644fad2fb9dfa5886c9dc1b..75afa73808123a9c9c53f6c083dbb76921d9b117 100644
--- a/pkg/analyzer/test/src/task/strong/checker_test.dart
+++ b/pkg/analyzer/test/src/task/strong/checker_test.dart
@@ -988,7 +988,7 @@ Stream<int> bar4() async* { yield /*error:YIELD_OF_INVALID_TYPE*/new Stream<int>
 
 baz1() async* { yield* /*info:DYNAMIC_CAST*/x; }
 Stream baz2() async* { yield* /*info:DYNAMIC_CAST*/x; }
-Stream<int> baz3() async* { yield* /*warning:DOWN_CAST_COMPOSITE*/x; }
+Stream<int> baz3() async* { yield* /*info:DYNAMIC_CAST*/x; }
 Stream<int> baz4() async* { yield* new Stream<int>(); }
 Stream<int> baz5() async* { yield* /*info:INFERRED_TYPE_ALLOCATION*/new Stream(); }
 ''');
@@ -1005,7 +1005,7 @@ Iterable<int> bar4() sync* { yield /*error:YIELD_OF_INVALID_TYPE*/bar3(); }
 
 baz1() sync* { yield* /*info:DYNAMIC_CAST*/x; }
 Iterable baz2() sync* { yield* /*info:DYNAMIC_CAST*/x; }
-Iterable<int> baz3() sync* { yield* /*warning:DOWN_CAST_COMPOSITE*/x; }
+Iterable<int> baz3() sync* { yield* /*info:DYNAMIC_CAST*/x; }
 Iterable<int> baz4() sync* { yield* bar3(); }
 Iterable<int> baz5() sync* { yield* /*info:INFERRED_TYPE_ALLOCATION*/new List(); }
 ''');