Make isEmpty a getter.

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.
 
 String unparse(Node node) {
   Unparser unparser = new Unparser();
   unparser.unparse(node);
   return unparser.result;
 }
 
@@ skipping 42 matching lines @@
     }
     visit(node.name);
     if (node.typeParameters != null) {
       visit(node.typeParameters);
     }
     if (node.extendsKeyword != null) {
       sb.add(' ');
       addToken(node.extendsKeyword);
       visit(node.superclass);
     }
-    if (!node.interfaces.isEmpty()) {
+    if (!node.interfaces.isEmpty) {
       sb.add(' ');
       visit(node.interfaces);
     }
     if (node.defaultClause != null) {
       sb.add(' default ');
       visit(node.defaultClause);
     }
     sb.add('{');
     for (final member in members) {
       visit(member);
@@ skipping 125 matching lines @@
   visitNewExpression(NewExpression node) {
     addToken(node.newToken);
     visit(node.send);
   }
 
   visitLiteralList(LiteralList node) {
     if (node.constKeyword != null) add(node.constKeyword.value);
     visit(node.typeArguments);
     visit(node.elements);
     // If list is empty, emit space after [] to disambiguate cases like []==[].
-    if (node.elements.isEmpty()) sb.add(' ');
+    if (node.elements.isEmpty) sb.add(' ');
   }
 
   visitModifiers(Modifiers node) => node.visitChildren(this);
 
   /**
    * Unparses given NodeList starting from specific node.
    */
   unparseNodeListFrom(NodeList node, Link<Node> from) {
-    if (from.isEmpty()) return;
+    if (from.isEmpty) return;
     String delimiter = (node.delimiter == null) ? "" : "${node.delimiter}";
     visit(from.head);
-    for (Link link = from.tail; !link.isEmpty(); link = link.tail) {
+    for (Link link = from.tail; !link.isEmpty; link = link.tail) {
       sb.add(delimiter);
       visit(link.head);
     }
   }
 
   visitNodeList(NodeList node) {
     addToken(node.beginToken);
     if (node.nodes != null) {
       unparseNodeListFrom(node, node.nodes);
     }
@@ skipping 359 matching lines @@
   }
 
   visitStatement(Statement node) {
     throw 'internal error'; // Should not be called.
   }
 
   visitStringNode(StringNode node) {
     throw 'internal error'; // Should not be called.
   }
 }