Make continue work in do-while.

frog/leg/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
 }
 
 class TreeElementMapping implements TreeElements {
@@ skipping 1033 matching lines @@
   }
 
   visitContinueStatement(ContinueStatement node) {
     TargetElement target;
     if (node.target === null) {
       target = statementScope.currentContinueTarget();
       if (target === null) {
         error(node, MessageKind.NO_CONTINUE_TARGET);
         return;
       }
+      target.isContinueTarget = true;
     } else {
       String labelName = node.target.source.slowToString();
       LabelElement label = statementScope.lookupLabel(labelName);
       if (label === null) {
         error(node.target, MessageKind.UNBOUND_LABEL, [labelName]);
         return;
       }
       target = label.target;
       if (!target.statement.isValidContinueTarget()) {
         error(node.target, MessageKind.INVALID_CONTINUE, [labelName]);
       }
+      label.setContinueTarget();
     }
-    target.isContinueTarget = true;
     mapping[node] = target;
   }
 
   visitForInStatement(ForInStatement node) {
     visit(node.expression);
     Scope scope = new BlockScope(context);
     Node declaration = node.declaredIdentifier;
     visitIn(declaration, scope);
     visitLoopBodyIn(node, node.body, scope);
 
@@ skipping 699 matching lines @@
 
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) {
     return library.find(name);
   }
 
   Element add(Element element) {
     throw "Cannot add an element in the top scope";
   }
 }