[polymer] fix editor hints -- query/queryAll and unused imports

pkg/polymer/lib/src/build/linter.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.
 
 /**
  * Logic to validate that developers are correctly using Polymer constructs.
  * This is mainly used to produce warnings for feedback in the editor.
  */
 library polymer.src.build.linter;
 
-import 'dart:io';
 import 'dart:async';
-import 'dart:mirrors';
-import 'dart:convert' show JSON;
 
 import 'package:barback/barback.dart';
 import 'package:html5lib/dom.dart';
 import 'package:html5lib/dom_parsing.dart';
 import 'package:source_maps/span.dart';
 
 import 'common.dart';
 import 'utils.dart';
 
 /**
@@ skipping 47 matching lines @@
     if (id == null || seen.contains(id)) return new Future.value(null);
     seen.add(id);
     return readAsHtml(id, transform).then(
         (doc) => _collectElements(doc, id, transform, seen, elements));
   }
 
   Future<List<AssetId>> _getImportedIds(
       Document document, AssetId sourceId, Transform transform) {
     var importIds = [];
     var logger = transform.logger;
-    for (var tag in document.queryAll('link')) {
+    for (var tag in document.querySelectorAll('link')) {
       if (tag.attributes['rel'] != 'import') continue;
       var href = tag.attributes['href'];
       var span = tag.sourceSpan;
       var id = resolve(sourceId, href, logger, span);
       if (id == null ||
           (id.package == 'polymer' && id.path == 'lib/init.html')) continue;
       importIds.add(assetExists(id, transform).then((exists) {
         if (exists) return id;
         if (sourceId == transform.primaryInput.id) {
           logger.error('couldn\'t find imported asset "${id.path}" in package '
               '"${id.package}".', span: span);
         }
       }));
     }
     return Future.wait(importIds);
   }
 
   void _addElements(Document document, TransformLogger logger,
       Map<String, _ElementSummary> elements) {
-    for (var tag in document.queryAll('polymer-element')) {
+    for (var tag in document.querySelectorAll('polymer-element')) {
       var name = tag.attributes['name'];
       if (name == null) continue;
       var extendsTag = tag.attributes['extends'];
       var span = tag.sourceSpan;
       var existing = elements[name];
       if (existing != null) {
 
         // Report warning only once.
         if (existing.hasConflict) continue;
         existing.hasConflict = true;
@@ skipping 341 matching lines @@
     'Make sure the script tag is placed after all HTML imports.';
 
 const String BOOT_JS_DEPRECATED =
     '"boot.js" is now deprecated. Instead, you can initialize your polymer '
     'application by calling "initPolymer()" in your main. If you don\'t have a '
     'main, then you can include our generic main by adding the following '
     'script tag to your page: \'<script type="application/dart">export '
     '"package:polymer/init.dart";</script>\'. Additionally you need to '
     'include: \'<script src="packages/browser/dart.js"></script>\' in the page '
     'too. Make sure these script tags come after all HTML imports.';