Add copyright header to generated analyzer files.

pkg/analyzer/lib/src/generated/html.dart

+// 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.
+
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.html;
 
 import 'dart:collection';
 import 'java_core.dart';
 import 'java_engine.dart';
 import 'source.dart';
 import 'error.dart' show AnalysisErrorListener;
@@ skipping 2169 matching lines @@
     }
     super.element = element;
   }
 
   void visitChildren(XmlVisitor visitor) {
     for (XmlTagNode node in _tagNodes) {
       node.accept(visitor);
     }
   }
 }