fixes #27586, prefer context type in generic inference

tests/language_strong/recursive_generic_test.dart

Index: tests/language_strong/recursive_generic_test.dart
diff --git a/tests/language_strong/recursive_generic_test.dart b/tests/language_strong/recursive_generic_test.dart
index 3d8dcd642f89d8cf420ca22e290b4e36d97fbf73..96f22c198c40abc359f44b7979b6e61b4d4931e8 100644
--- a/tests/language_strong/recursive_generic_test.dart
+++ b/tests/language_strong/recursive_generic_test.dart
@@ -7,10 +7,12 @@ import "package:expect/expect.dart";
 abstract class S<T extends S<T>> { m() => 123; get S_T => T; }
 class C<T extends C<T>> extends S<C> { m() => 456; get C_T => T; }
 
+class D extends C<D> {}
+
 main() {
-  Expect.equals(new C().m(), 456);
+  Expect.equals(new C<D>().m(), 456);
   // TODO(jmesserly): this should be dart1 vs dart2, not DDC vs VM.
   var isVM = const bool.fromEnvironment('dart.isVM');
-  Expect.equals(new C().S_T.toString(), isVM ? 'C' : 'C<C>');
-  Expect.equals(new C().C_T.toString(), isVM ? 'dynamic' : 'C');
+  Expect.equals(new C<D>().S_T.toString(), isVM ? 'C' : 'C<C>');
+  Expect.equals(new C<D>().C_T.toString(), isVM ? 'dynamic' : 'D');
 }