Remove stale files from lib/html/src.

lib/html/src/ErrorEvent.dart

Index: lib/html/src/ErrorEvent.dart
diff --git a/lib/html/src/ErrorEvent.dart b/lib/html/src/ErrorEvent.dart
deleted file mode 100644
index 2e1a8d198a9697567d08053836ef5e8293302a89..0000000000000000000000000000000000000000
--- a/lib/html/src/ErrorEvent.dart
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright (c) 2011, 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.
-
-interface ErrorEvent extends Event default ErrorEventWrappingImplementation {
-
-  ErrorEvent(String type, String message, String filename, int lineNo,
-      [bool canBubble, bool cancelable]);
-
-  String get filename();
-
-  int get lineno();
-
-  String get message();
-}