Add support for 'Dynamic' type in the VM.

tests/language/src/GenericTest.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.
 // VMOptions=--enable_type_checks --enable_asserts
 //
 // Dart test program testing generic type allocations and generic type tests.
 
 class A {
   const A();
 }
@@ skipping 30 matching lines @@
   E() : cax_ = new C<AX>(const AX()) { }
 }
 
 class GenericTest {
   static test() {
     int result = 0;
     try {
       D d = new D();
       Expect.equals(true, d.caa_.b_ is B<AA>);
       Expect.equals(true, d.caa_.b_.isT(const AA()));
-      C c = new C(const AA());  // c is of raw type C, T in C<T> is VarType.
+      C c = new C(const AA());  // c is of raw type C, T in C<T> is Dynamic.
       Expect.equals(true, c.b_ is B);
       Expect.equals(true, c.b_ is B<AA>);
       Expect.equals(true, c.b_.isT(const AA()));
       Expect.equals(true, c.b_.isT(const AX()));
       E e = new E();  // Throws a type error, if type checks are enabled.
     } catch (TypeError error) {
       result = 1;
       // TODO(regis): The error below is detected too late.
       // It should be reported on line 26, at new B<AX>().
       // This will be detected when we check the subtyping constraints.
@@ skipping 14 matching lines @@
 
   static testMain() {
     Expect.equals(1, test());
   }
 }
 
 
 main() {
   GenericTest.testMain();
 }