Start supporting default classes.

dart/frog/leg/elements/elements.dart

 // Copyright (c) 2012, 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.
 
 #library('elements');
 
 #import('../tree/tree.dart');
 #import('../scanner/scannerlib.dart');
 #import('../leg.dart');  // TODO(karlklose): we only need type.
 #import('../util/util.dart');
@@ skipping 473 matching lines @@
         null, null, null, null);
     return cachedNode;
   }
 
   Token position() => null;
 }
 
 class ClassElement extends ContainerElement {
   Type type;
   Type supertype;
+  Type defaultClass;
   Link<Element> members = const EmptyLink<Element>();
   Map<SourceString, Element> localMembers;
   Map<SourceString, Element> constructors;
   Link<Type> interfaces = const EmptyLink<Type>();
   bool isResolved = false;
   // backendMembers are members that have been added by the backend to simplify
   // compilation. They don't have any user-side counter-part.
   Link<Element> backendMembers = const EmptyLink<Element>();
   SynthesizedConstructorElement synthesizedConstructor;
 
@@ skipping 101 matching lines @@
 
   /**
    * Returns the super class, if any.
    *
    * The returned element may not be resolved yet.
    */
   ClassElement get superclass() {
     assert(isResolved);
     return supertype === null ? null : supertype.element;
   }
+
+  bool isInterface() => false;
 }
 
 class Elements {
   static bool isLocal(Element element) {
     return ((element !== null)
             && !element.isInstanceMember()
             && !isStaticOrTopLevelField(element)
             && !isStaticOrTopLevelFunction(element)
             && (element.kind === ElementKind.VARIABLE ||
                 element.kind === ElementKind.PARAMETER ||
@@ skipping 94 matching lines @@
   bool isContinueTarget = false;
 
   StatementElement(this.origin, Element enclosingElement)
       : super(const SourceString(""), ElementKind.STATEMENT, enclosingElement);
   StatementElement.label(String name, this.origin, Element enclosingElement)
       : super(new SourceString(name), ElementKind.STATEMENT, enclosingElement);
   bool get isTarget() => isBreakTarget || isContinueTarget;
 
   Node parseNode(DiagnosticListener l) => origin;
 }