Make a single labeled statement hold all its labels.

lib/compiler/implementation/tree/nodes.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 Visitor<R> {
   R visitBlock(Block node);
   R visitBreakStatement(BreakStatement node);
   R visitCascade(Cascade node);
   R visitCascadeReceiver(CascadeReceiver node);
   R visitCaseMatch(CaseMatch node);
@@ skipping 1456 matching lines @@
 
   void visitChildren(Visitor visitor) {
     identifier.accept(visitor);
   }
 
   Token getBeginToken() => identifier.token;
   Token getEndToken() => colonToken;
 }
 
 class LabeledStatement extends Statement {
-  final Label label;
+  final NodeList labels;
   final Statement statement;
 
-  LabeledStatement(this.label, this.statement);
+  LabeledStatement(this.labels, this.statement);
 
   LabeledStatement asLabeledStatement() => this;
 
   accept(Visitor visitor) => visitor.visitLabeledStatement(this);
 
   visitChildren(Visitor visitor) {
-    label.accept(visitor);
+    labels.accept(visitor);
     statement.accept(visitor);
   }
 
-  Token getBeginToken() => label.getBeginToken();
+  Token getBeginToken() => labels.getBeginToken();
 
   Token getEndToken() => statement.getEndToken();
 
   bool isValidContinueTarget() => statement.isValidContinueTarget();
 
-  Node getBody() {
-    if (statement is! LabeledStatement) return statement;
-    LabeledStatement labeled = statement;
-    return labeled.getBody();
-  }
+  Node getBody() => statement;
 }
 
 class ScriptTag extends Node {
   final Identifier tag;
   final StringNode argument;
   final Identifier prefixIdentifier;
   final StringNode prefix;
 
   final Token beginToken;
   final Token endToken;
@@ skipping 192 matching lines @@
  * argument).
  *
  * TODO(ahe): This method is controversial, the team needs to discuss
  * if top-level methods are acceptable and what naming conventions to
  * use.
  */
 initializerDo(Node node, f(Node node)) {
   SendSet send = node.asSendSet();
   if (send !== null) return f(send.arguments.head);
 }