Add linter by default for polymer's pub-build, also cleans up the linter code.

pkg/polymer/lib/src/build/import_inliner.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.
 
 /** Transfomer that inlines polymer-element definitions from html imports. */
 library polymer.src.build.import_inliner;
 
 import 'dart:async';
 import 'dart:convert';
 
@@ skipping 132 matching lines @@
    */
   Future _collectImportedDocuments(AssetId id, Transform transform,
       Set<AssetId> seen, List documents) {
     return readAsHtml(id, transform).then((document) {
       return _visitImports(document, id, transform, seen, documents).then((_) {
         new _UrlNormalizer(transform, id).visit(document);
         documents.add(document);
       });
     });
   }
+
+  String toString() => 'polymer-import-inliner';
 }
 
 /** Internally adjusts urls in the html that we are about to inline. */
 class _UrlNormalizer extends TreeVisitor {
   final Transform transform;
 
   /** Asset where the original content (and original url) was found. */
   final AssetId sourceId;
 
   _UrlNormalizer(this.transform, this.sourceId);
@@ skipping 55 matching lines @@
   'cite',       // in blockquote, del, ins, q
   'data',       // in object
   'formaction', // in button, input
   'href',       // in a, area, link, base, command
   'icon',       // in command
   'manifest',   // in html
   'poster',     // in video
   'src',        // in audio, embed, iframe, img, input, script, source, track,
                 //    video
 ];