Make isEmpty a getter.

lib/compiler/implementation/dart_backend/utils.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 CloningVisitor implements Visitor<Node> {
   final TreeElements originalTreeElements;
   final TreeElementMapping cloneTreeElements;
 
   CloningVisitor(this.originalTreeElements)
       : cloneTreeElements = new TreeElementMapping();
@@ skipping 110 matching lines @@
   visitNewExpression(NewExpression node) => new NewExpression(
       node.newToken, visit(node.send));
 
   rewriteNodeList(NodeList node, Link link) =>
       new NodeList(node.beginToken, link, node.endToken, node.delimiter);
 
   visitNodeList(NodeList node) {
     // Special case for classes which exist in hierarchy, but not
     // in the visitor.
     if (node is Prefix) {
-      return node.nodes.isEmpty() ?
+      return node.nodes.isEmpty ?
           new Prefix() : new Prefix.singleton(visit(node.nodes.head));
     }
     if (node is Postfix) {
-      return node.nodes.isEmpty() ?
+      return node.nodes.isEmpty ?
           new Postfix() : new Postfix.singleton(visit(node.nodes.head));
     }
     LinkBuilder<Node> builder = new LinkBuilder<Node>();
     for (Node n in node.nodes) {
       builder.addLast(visit(n));
     }
     return rewriteNodeList(node, builder.toLink());
   }
 
   visitOperator(Operator node) => new Operator(node.token);
@@ skipping 122 matching lines @@
   }
 
   Node visitStringNode(StringNode node) {
     unimplemented('visitNode', node: node);
   }
 
   unimplemented(String message, {Node node}) {
     throw message;
   }
 }