Switch polymer's build.dart to use the new linter. This CL does the following

pkg/polymer/lib/src/transform/common.dart

 // Copyright (c) 2013, 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 methods used by transfomers. */
 library polymer.src.transform.common;
 
 import 'dart:async';
 
 import 'package:barback/barback.dart';
@@ skipping 16 matching lines @@
   // Note: errors aren't fatal in HTML (unless strict mode is on).
   // So just print them as warnings.
   for (var e in parser.errors) {
     if (checkDocType || e.errorCode != 'expected-doctype-but-got-start-tag') {
       logger.warning(e.message, e.span);
     }
   }
   return document;
 }
 
-Future<Document> readPrimaryAsHtml(Transform transform) {
-  var asset = transform.primaryInput;
-  var id = asset.id;
-  return asset.readAsString().then((content) {
-    return _parseHtml(content, id.path, transform.logger,
-      checkDocType: isPrimaryHtml(id));
-  });
+/** Additional options used by polymer transformers */
+class TransformOptions {
+  String currentPackage;
+  List<String> entrypoints;
+
+  TransformOptions([this.currentPackage, this.entrypoints]);
+
+  /** Whether an asset with [id] is an entry point HTML file. */
+  bool isHtmlEntrypoint(AssetId id) {

[Jennifer Messerly, 2013/09/10 04:16:51]

nit: entry point is two words? so entryPoint

(funny example:
http://msdn.microsoft.com/en-us/library/system.entrypointnotfoundexception.aspx)

[Siggi Cherem (dart-lang), 2013/09/11 01:45:26]

Done.

+    if (id.extension != '.html') return false;
+
+    // Note: [id.path] is a relative path from the root of a package.
+    if (!id.path.startsWith('web/') &&
+        !id.path.startsWith('test/')) return false;
+
+    if (currentPackage == null || entrypoints == null) return true;
+    return id.package == currentPackage && entrypoints.contains(id.path);
+  }
 }
 
-Future<Document> readAsHtml(AssetId id, Transform transform) {
-  var primaryId = transform.primaryInput.id;
-  var url = (id.package == primaryId.package) ? id.path
-      : assetUrlFor(id, primaryId, transform.logger, allowAssetUrl: true);
-  return transform.readInputAsString(id).then((content) {
-    return _parseHtml(content, url, transform.logger,
-      checkDocType: isPrimaryHtml(id));
-  });
+/** Mixin for polymer transformers. */
+abstract class PolymerTransformer {
+  TransformOptions get options;
+
+  Future<Document> readPrimaryAsHtml(Transform transform) {
+    var asset = transform.primaryInput;
+    var id = asset.id;
+    return asset.readAsString().then((content) {
+      return _parseHtml(content, id.path, transform.logger,
+        checkDocType: options.isHtmlEntrypoint(id));
+    });
+  }
+
+  Future<Document> readAsHtml(AssetId id, Transform transform) {
+    var primaryId = transform.primaryInput.id;
+    var url = (id.package == primaryId.package) ? id.path
+        : assetUrlFor(id, primaryId, transform.logger, allowAssetUrl: true);
+    return transform.readInputAsString(id).then((content) {
+      return _parseHtml(content, url, transform.logger,
+        checkDocType: options.isHtmlEntrypoint(id));
+    });
+  }
 }
 
 /** Create an [AssetId] for a [url] seen in the [source] asset. */
 // TODO(sigmund): delete once this is part of barback (dartbug.com/12610)
 AssetId resolve(AssetId source, String url, TransformLogger logger, Span span) {
   if (url == null || url == '') return null;
   var uri = Uri.parse(url);
   var urlBuilder = path.url;
   if (uri.host != '' || uri.scheme != '' || urlBuilder.isAbsolute(url)) {
     logger.error('absolute paths not allowed: "$url"', span);
@@ skipping 21 matching lines @@
     targetPath = urlBuilder.join('asset',
         urlBuilder.joinAll(segments.sublist(2)));
   } else {
     package = source.package;
     targetPath = urlBuilder.normalize(
         urlBuilder.join(urlBuilder.dirname(source.path), url));
   }
   return new AssetId(package, targetPath);
 }
 
-/** Whether an asset with [id] is considered a primary entry point HTML file. */
-bool isPrimaryHtml(AssetId id) => id.extension == '.html' &&
-    // Note: [id.path] is a relative path from the root of a package.
-    (id.path.startsWith('web/') || id.path.startsWith('test/'));
-
 /**
  * Generate the import url for a file described by [id], referenced by a file
  * with [sourceId].
  */
 // TODO(sigmund): this should also be in barback (dartbug.com/12610)
 String assetUrlFor(AssetId id, AssetId sourceId, TransformLogger logger,
     {bool allowAssetUrl: false}) {
   // use package: and asset: urls if possible
   if (id.path.startsWith('lib/')) {
     return 'package:${id.package}/${id.path.substring(4)}';
@@ skipping 11 matching lines @@
   // Use relative urls only if it's possible.
   if (id.package != sourceId.package) {
     logger.error("don't know how to refer to $id from $sourceId");
     return null;
   }
 
   var builder = path.url;
   return builder.relative(builder.join('/', id.path),
       from: builder.join('/', builder.dirname(sourceId.path)));
 }