Unify the server and plugin versions of the generators

pkg/analyzer_plugin/tool/spec/from_html.dart

-// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2014, 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.
 
 /**
  * Code for reading an HTML API description.
  */
 import 'dart:io';
 
 import 'package:analyzer/src/codegen/html.dart';
 import 'package:html/dom.dart' as dom;
@@ skipping 540 matching lines @@
       TypeDefinition typeDefinition = typeDefinitionFromHtml(child);
       types[typeDefinition.name] = typeDefinition;
     }
   });
   return new Types(types, html);
 }
 
 typedef void ElementProcessor(dom.Element element);
 
 typedef void TextProcessor(dom.Text text);