Fix a bunch of issues with 'hidden' DOM types.

tests/language/src/NativeClassIsCheck2FrogTest.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.
 
 // Test for correct is-checks on hidden native classes.
 
 interface I {
   I read();
   write(I x);
 }
 
 // Native implementation.
 
 class A implements I native "*A" {
   // The native class accepts only other native instances.
   A read() native;
   write(A x) native;
 }
 
 makeA() native;
 
 void setup() native """
 // This code is all inside 'setup' and so not accesible from the global scope.
 function A(){}
 A.prototype.read = function() { return this._x; };
 A.prototype.write = function(x) { this._x = x; };
+makeA = function(){return new A};
 """;
 
 // Dart implementation must coexist with native implementation.
 
 class B implements I {
   B b;
   B read() { return b; }
   write(B x) { b = x; }
 }
 
@@ skipping 45 matching lines @@
     var ob = new Object();
     Expect.isTrue(ob is !T);
     Expect.isTrue(x is T);
     Expect.isTrue(y is T);
 
     // In checked mode, there is a parameterized type assertion in assignment.
     _x = x;
     _y = y;
   }
 }