Implement continue for switch.

sdk/lib/_internal/compiler/implementation/elements/modelx.dart

 // Copyright (c) 2013, 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.modelx;
 
 import 'dart:uri';
 import 'dart:collection' show LinkedHashMap;
 
 import 'elements.dart';
@@ skipping 1989 matching lines @@
 // Represents a reference to a statement or switch-case, either by label or the
 // default target of a break or continue.
 class TargetElementX extends ElementX implements TargetElement {
   final Node statement;
   final int nestingLevel;
   Link<LabelElement> labels = const Link<LabelElement>();
   bool isBreakTarget = false;
   bool isContinueTarget = false;
 
   TargetElementX(this.statement, this.nestingLevel, Element enclosingElement)
-      : super(const SourceString(""), ElementKind.STATEMENT, enclosingElement);
+      : super(const SourceString("target"),
+              ElementKind.STATEMENT, enclosingElement);
   bool get isTarget => isBreakTarget || isContinueTarget;
 
   LabelElement addLabel(Label label, String labelName) {
     LabelElement result = new LabelElementX(label, labelName, this,
                                             enclosingElement);
     labels = labels.prepend(result);
     return result;
   }
 
   Node parseNode(DiagnosticListener l) => statement;
@@ skipping 64 matching lines @@
 
   MetadataAnnotation ensureResolved(Compiler compiler) {
     if (resolutionState == STATE_NOT_STARTED) {
       compiler.resolver.resolveMetadataAnnotation(this);
     }
     return this;
   }
 
   String toString() => 'MetadataAnnotation($value, $resolutionState)';
 }