Restore old supermixin functionality to shared language tests.

tests/language/mixin_illegal_super_use_test.dart

Index: tests/language/mixin_illegal_super_use_test.dart
diff --git a/tests/language/mixin_super_use_test.dart b/tests/language/mixin_illegal_super_use_test.dart
similarity index 64%
copy from tests/language/mixin_super_use_test.dart
copy to tests/language/mixin_illegal_super_use_test.dart
index cd958467e19d76fbce47e73ec36d1ad0c7bb9270..7f0d64a39de0173b8d9520ae6c9decd24064d1d4 100644
--- a/tests/language/mixin_super_use_test.dart
+++ b/tests/language/mixin_illegal_super_use_test.dart
@@ -9,15 +9,21 @@ class M {
 
 class P0 {
   foo() {
-    super.toString();
+    super.toString();    /// 01: compile-time error
+    super.foo();         /// 02: compile-time error
+    super.bar = 100;     /// 03: compile-time error
 
     void inner() {
-      super.toString();
+      super.toString();  /// 04: compile-time error
+      super.foo();       /// 05: compile-time error
+      super.bar = 100;   /// 06: compile-time error
     }
     inner();
 
     (() {
-      super.toString();
+      super.toString();  /// 07: compile-time error
+      super.foo();       /// 08: compile-time error
+      super.bar = 100;   /// 09: compile-time error
     })();
 
     return 42;
@@ -26,7 +32,7 @@ class P0 {
 
 class P1 {
   bar() {
-    super.toString();
+    super.toString();    /// 10: compile-time error
     return 87;
   }
 
@@ -46,7 +52,7 @@ class P1 {
 
 class P2 {
   baz() {
-    super.toString();
+    super.toString();   /// 11: compile-time error
     return 99;
   }
 }