Update utils to new library syntax.

utils/apidoc/scripts/list_files.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.
 
 /**
  * Traverses apidoc and dartdoc and lists all possible input files that are
  * used when building API documentation. Used by gyp to determine when apidocs
  * need to be regenerated (see `apidoc.gyp`).
  */
-#library('list_files');
+library list_files;
 
-#import('dart:io');
+import 'dart:io';
 
 const allowedExtensions = const [
   '.css', '.dart', '.ico', '.js', '.json', '.png', '.sh', '.txt'
 ];
 
 void main() {
   final scriptDir = new File(new Options().script).directorySync().path;
   final dartDir = '$scriptDir/../../../';
   listFiles('$dartDir/utils/apidoc');
   listFiles('$dartDir/sdk/lib/_internal/dartdoc');
@@ skipping 10 matching lines @@
 
   dir.list(recursive: true);
 }
 
 String extension(String path) {
   int lastDot = path.lastIndexOf('.');
   if (lastDot == -1) return '';
 
   return path.substring(lastDot);
 }