[pkg:web_ui] fix insertBefore case

lib/src/emitters.dart

 // Copyright (c) 2012, 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.
 
 /** Collects several code emitters for the template tool. */
 library emitters;
 
 import 'package:csslib/parser.dart' as css;
 import 'package:csslib/visitor.dart';
 import 'package:html5lib/dom.dart';
@@ skipping 903 matching lines @@
   var bootstrapScript = parseFragment(
         '<script type="application/dart" src="$bootstrapOutName"></script>');
   if (dartLoaderTag == null) {
     document.body.nodes.add(bootstrapScript);
     document.body.nodes.add(parseFragment(
         '<script type="text/javascript" src="packages/browser/dart.js">'
         '</script>\n'));
   } else if (dartLoaderTag.parent != document.body) {
     document.body.nodes.add(bootstrapScript);
   } else {
-    document.body.nodes.insertBefore(bootstrapScript, dartLoaderTag);
+    document.body.insertBefore(bootstrapScript, dartLoaderTag);
   }
 
   // Insert the "auto-generated" comment after the doctype, otherwise IE will
   // go into quirks mode.
   int commentIndex = 0;
   DocumentType doctype = find(document.nodes, (n) => n is DocumentType);
   if (doctype != null) {
     commentIndex = document.nodes.indexOf(doctype) + 1;
     // TODO(jmesserly): the html5lib parser emits a warning for missing
     // doctype, but it allows you to put it after comments. Presumably they do
@@ skipping 17 matching lines @@
   return """
 // Auto-generated from $filename.
 // DO NOT EDIT.
 $lib
 import 'dart:html' as autogenerated;
 import 'dart:svg' as autogenerated_svg;
 import 'package:web_ui/web_ui.dart' as autogenerated;
 import 'package:web_ui/observe/observable.dart' as __observe;
 """;
 }