fix more mixin tests to work in strong mode

tests/language_strong/mixin_type_parameters_super_extends_test.dart

Index: tests/language_strong/mixin_type_parameters_super_extends_test.dart
diff --git a/tests/language_strong/mixin_type_parameters_super_extends_test.dart b/tests/language_strong/mixin_type_parameters_super_extends_test.dart
index cdebe98257f8769be7babc25aac57e89effc8ec9..a21e2c3f8499476f307878b84ba1daaded826e9c 100644
--- a/tests/language_strong/mixin_type_parameters_super_extends_test.dart
+++ b/tests/language_strong/mixin_type_parameters_super_extends_test.dart
@@ -29,7 +29,7 @@ class S<T> {
   static final bool checkedMode = computeCheckedMode();
   static bool computeCheckedMode() {
     try {
-      int x = "foo";
+      int x = "foo" as dynamic;
     } on Error {
       return true;
     }
@@ -50,32 +50,32 @@ class C3 extends S<String> with M {}
 main() {
   var c0 = new C0();
   Expect.isTrue(c0 is S);
-  Expect.isTrue(c0 is S<int>);
-  Expect.isTrue(c0 is S<String>);
+  Expect.isFalse(c0 is S<int>);
+  Expect.isFalse(c0 is S<String>);
   Expect.isTrue(c0.matches(c0));
   Expect.isTrue(c0.matches(42));
   Expect.isTrue(c0.matches("hello"));
 
   var c0_int = new C0<int>();
   Expect.isTrue(c0_int is S);
-  Expect.isTrue(c0_int is S<int>);
-  Expect.isTrue(c0_int is S<String>);
+  Expect.isFalse(c0_int is S<int>);
+  Expect.isFalse(c0_int is S<String>);
   Expect.isTrue(c0_int.matches(c0));
   Expect.isTrue(c0_int.matches(42));
   Expect.isTrue(c0_int.matches("hello"));
 
   var c0_String = new C0<String>();
   Expect.isTrue(c0_String is S);
-  Expect.isTrue(c0_String is S<int>);
-  Expect.isTrue(c0_String is S<String>);
+  Expect.isFalse(c0_String is S<int>);
+  Expect.isFalse(c0_String is S<String>);
   Expect.isTrue(c0_String.matches(c0));
   Expect.isTrue(c0_String.matches(42));
   Expect.isTrue(c0_String.matches("hello"));
 
   var c1 = new C1();
   Expect.isTrue(c1 is S);
-  Expect.isTrue(c1 is S<int>);
-  Expect.isTrue(c1 is S<String>);
+  Expect.isFalse(c1 is S<int>);
+  Expect.isFalse(c1 is S<String>);
   Expect.isTrue(c1.matches(c1));
   Expect.isTrue(c1.matches(42));
   Expect.isTrue(c1.matches("hello"));