Add more options to configure the linter.

pkg/polymer/lib/src/build/linter.dart

Index: pkg/polymer/lib/src/build/linter.dart
diff --git a/pkg/polymer/lib/src/build/linter.dart b/pkg/polymer/lib/src/build/linter.dart
index 15100e66ac4f27f904a2487080bb8a6234488c9b..4451a8e7e33135c4832cd5b2cbc7a6bbe253af20 100644
--- a/pkg/polymer/lib/src/build/linter.dart
+++ b/pkg/polymer/lib/src/build/linter.dart
@@ -27,11 +27,11 @@ import 'messages.dart';
 class Linter extends Transformer with PolymerTransformer {
   final TransformOptions options;
 
-  /// Only run on .html files.
-  final String allowedExtensions = '.html';
-
   Linter(this.options);
 
+  isPrimary(AssetId id) =>
+      id.extension == '.html' && options.lint.shouldLint(id.path);
+
   Future apply(Transform transform) {
     var seen = new Set<AssetId>();
     var primary = transform.primaryInput;