Fix type checking of void type.

tests/language/generics_test.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // Dart test for generic types.
 
 class GenericsTest<T,V> implements Map<int, int> {
   static int myFunc(bool a, bool b) {
     Expect.equals(true, a);
     Expect.equals(false, b);
     return 42;
   }
 
   static void testMain() {
     int a = 1;
     int b = 2;
     int c = 3;
     int d = 4;
     Expect.equals(true, a<b);
     Expect.equals(42, myFunc(a<b, c> d));
     Map<int, int> e;
     GenericsTest<int, GenericsTest<int, int>> f;
 
     takesVoidMethod(void _(int a) {
       Expect.equals(2, a);
-      return 99;
     });
 
     takesGenericMapMethod(Map<int, int> _(int a) {
       Expect.equals(2, a);
       return null;
     });
 
     takesIntMethod(int _(int a) {
       Expect.equals(2, a);
       return 98;
     });
 
     e = new Map();
     takesMapMethod(e);
     Expect.equals(2, e[0]);
     Map h = new Map<int, int>();
   }
 
   static void takesVoidMethod(void f(int a)) {
-    Expect.equals(99, f(2));
+    f(2);
   }
 
   static void takesIntMethod(int f(int a)) {
     Expect.equals(98, f(2));
   }
 
   static void takesGenericMapMethod(Map<int, int> f(int a)) {
     f(2);
   }
 
@@ skipping 21 matching lines @@
         LongGeneric<
             C,
             List<E>,
             Map<G, LongGeneric<I, J, List<A>>>>> id2;
   }
 }
 
 main() {
   GenericsTest.testMain();
 }