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

frog/type.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.
 
 class Type extends Element {
-  bool isTested;
+  bool isTested = false;
+  bool isChecked = false;
 
   /**
    * For core types (int, String, etc) this is the generated type assertion
    * function (uses JS "typeof"). This field is null for all other types.
    */
   String typeCheckCode;
 
   Member _typeMember;
 
-  /** Stubs used to call into this method dynamically. Lazy initialized. */
+  /** Stubs used to call into this method dynamically. */
   Map<String, VarMember> varStubs;
 
   /** Cache of [MemberSet]s that have been resolved. */
   Map<String, MemberSet> _resolvedMembers;
 
-  Type(String name): isTested = false, _resolvedMembers = {}, super(name, null);
+  Type(String name): _resolvedMembers = {}, varStubs = {}, super(name, null);
 
   void markUsed() {}
   abstract void genMethod(Member method);
 
   TypeMember get typeMember() {
     if (_typeMember == null) {
       _typeMember = new TypeMember(this);
     }
     return _typeMember;
   }
@@ skipping 691 matching lines @@
   }
 
   void setDefinition(Definition def) {
     assert(definition == null);
     definition = def;
     if (definition is TypeDefinition && definition.nativeType != null) {
       isNative = true;
     }
     if (definition != null && definition.typeParameters != null) {
       _concreteTypes = {};