Handle labelled continue statements

pkg/compiler/lib/src/elements/jumps.dart

 // Copyright (c) 2017, 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.jumps;
 
 import 'entities.dart';
 
 /// The label entity defined by a labeled statement.
 abstract class LabelDefinition<T> extends Entity {
-  T get label;
   String get labelName;
   JumpTarget<T> get target;
 
   bool get isTarget => isBreakTarget || isContinueTarget;
 
   bool get isBreakTarget;
   bool get isContinueTarget;
 }
 
 /// A jump target is the reference point of a statement or switch-case,
 /// either by label or as the default target of a break or continue.
 abstract class JumpTarget<T> extends Local {
   String get name => 'target';
 
   bool get isTarget => isBreakTarget || isContinueTarget;
 
   T get statement;
   int get nestingLevel;
   List<LabelDefinition<T>> get labels;
 
   bool get isBreakTarget;
   bool get isContinueTarget;
   bool get isSwitch;
+  bool get isSwitchCase;
 
   LabelDefinition<T> addLabel(covariant T label, String labelName,
-      {bool isBreakTarget: false});
+      {bool isBreakTarget: false, bool isContinueTarget: false});
 }