Add more options to configure the linter.

pkg/polymer/lib/builder.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.
 
 /// Common logic to make it easy to run the polymer linter and deploy tool.
 ///
 /// The functions in this library are designed to make it easier to create
 /// `build.dart` files. A `build.dart` file is a Dart script that can be invoked
 /// from the command line, but that can also invoked automatically by the Dart
 /// Editor whenever a file in your project changes or when selecting some menu
@@ skipping 328 matching lines @@
   if (transformers is! List) {
     print('Unexpected value for transformers, expected a List.');
     return null;
   }
 
   transformers.forEach((t) {
     if (t is! Map) return;
     var polymer = t['polymer'];
     if (polymer == null || polymer is! Map) return;
 
-    var parsedEntryPoints = readEntrypoints(polymer['entry_points']);
+    var parsedEntryPoints = readFileList(polymer['entry_points']);
     if (parsedEntryPoints == null) return;
 
     entryPoints.addAll(parsedEntryPoints);
   });
   return entryPoints.isEmpty ? null : entryPoints;
 }