Make a single labeled statement hold all its labels.

lib/compiler/implementation/tree/unparser.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.
 
 class Unparser implements Visitor {
   StringBuffer sb;
   final bool printDebugInfo;
 
   Unparser([this.printDebugInfo = false]);
 
@@ skipping 295 matching lines @@
     sb.add(') ');
     visit(node.body);
   }
 
   visitLabel(Label node) {
     visit(node.identifier);
     add(node.colonToken.value);
    }
 
   visitLabeledStatement(LabeledStatement node) {
-    visit(node.label);
-    sb.add(' ');
+    visit(node.labels);
     visit(node.statement);
   }
 
   visitLiteralMap(LiteralMap node) {
     // TODO(ahe): handle 'const'.
     if (node.typeArguments !== null) visit(node.typeArguments);
     visit(node.entries);
   }
 
   visitLiteralMapEntry(LiteralMapEntry node) {
@@ skipping 76 matching lines @@
       sb.add(' ');
     }
     visit(node.name);
     if (node.typeParameters !== null) {
       visit(node.typeParameters);
     }
     visit(node.formals);
     add(node.endToken.value);
   }
 }