Change "typedef" to "class" in core library and related tests.

tests/language/mixin_type_parameters_errors_test.dart

Index: tests/language/mixin_type_parameters_errors_test.dart
diff --git a/tests/language/mixin_type_parameters_errors_test.dart b/tests/language/mixin_type_parameters_errors_test.dart
index c5889e5be76f5056c2f3ec21ac4364bee8aaf50b..63448eaf8b17e2486462cc0cd920eb58aa9c2f17 100644
--- a/tests/language/mixin_type_parameters_errors_test.dart
+++ b/tests/language/mixin_type_parameters_errors_test.dart
@@ -9,8 +9,8 @@ class A<X> extends S<int> with M<double> { }
 class B<U, V> extends S with M<U, V> { }  /// 01: static type warning
 class C<A, B> extends S<A, int> with M { }  /// 02: static type warning
 
-typedef F<X> = S<X> with M<X>;
-typedef G = S<int> with M<double, double>;  /// 05: static type warning
+class F<X> = S<X> with M<X>;
+class G = S<int> with M<double, double>;  /// 05: static type warning
 
 main() {
   var a;
@@ -19,4 +19,4 @@ main() {
   a = new A<String, String>();  /// 03: static type warning
   a = new F<int>();
   a = new F<int, String>();   /// 04: static type warning
-} 
+}