Various mocks and tweaks to reduce cancels in Leg.

dart/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 931 matching lines @@
 
   visitLabelledStatement(LabelledStatement node) {
     String labelName = node.label.source.stringValue;
     StatementElement existingElement = statementScope.lookupLabel(labelName);
     if (existingElement !== null) {
       LabelledStatement declaration = existingElement.origin;
       warning(node.label, MessageKind.DUPLICATE_LABEL, [labelName]);
       warning(declaration.label, MessageKind.EXISTING_LABEL, [labelName]);
     }
     StatementElement element =
-        new StatementElement.Label(labelName, node, enclosingElement);
+        new StatementElement.label(labelName, node, enclosingElement);
     statementScope.enterLabelScope(labelName, element);
     visit(node.statement);
     statementScope.exitLabelScope();
     if (element.isTarget) {
       mapping[node] = element;
     } else {
       warning(node.label, MessageKind.UNUSED_LABEL, [labelName]);
     }
   }
 
@@ skipping 329 matching lines @@
 class TopScope extends Scope {
   LibraryElement get library() => element;
 
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) => library.find(name);
 
   Element add(Element element) {
     throw "Cannot add an element in the top scope";
   }
 }