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

pkg/polymer/lib/src/build/code_extractor.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 extracts inlined script code into separate assets. */
 library polymer.src.build.code_extractor;
 
 import 'dart:async';
 
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 16 matching lines @@
 
   /** Only run this transformer on .html files. */
   final String allowedExtensions = ".html";
 
   Future apply(Transform transform) {
     var input = transform.primaryInput;
     var id = transform.primaryInput.id;
     return readPrimaryAsHtml(transform).then((document) {
       int count = 0;
       bool htmlChanged = false;
-      for (var tag in document.queryAll('script')) {
+      for (var tag in document.querySelectorAll('script')) {
         // Only process tags that have inline Dart code
         if (tag.attributes['type'] != 'application/dart' ||
           tag.attributes.containsKey('src')) {
           continue;
         }
         htmlChanged = true;
 
         // Remove empty tags
         if (tag.nodes.length == 0) {
           tag.remove();
@@ skipping 28 matching lines @@
   var scanner = new Scanner(null, reader, errorListener);
   var token = scanner.tokenize();
   var unit = new Parser(null, errorListener).parseCompilationUnit(token);
   return unit.directives.any((d) => d is LibraryDirective);
 }
 
 class _ErrorCollector extends AnalysisErrorListener {
   final errors = <AnalysisError>[];
   onError(error) => errors.add(error);
 }