Remove stale files from lib/html/src.

lib/html/src/XMLHttpRequestProgressEvent.dart

Index: lib/html/src/XMLHttpRequestProgressEvent.dart
diff --git a/lib/html/src/XMLHttpRequestProgressEvent.dart b/lib/html/src/XMLHttpRequestProgressEvent.dart
deleted file mode 100644
index 839e1b07a0c14ec6d3d0c12477ec3c4ec21b3a15..0000000000000000000000000000000000000000
--- a/lib/html/src/XMLHttpRequestProgressEvent.dart
+++ /dev/null
@@ -1,13 +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 XMLHttpRequestProgressEvent extends ProgressEvent default XMLHttpRequestProgressEventWrappingImplementation {
-
-  XMLHttpRequestProgressEvent(String type, int loaded, [bool canBubble,
-      bool cancelable, bool lengthComputable, int total]);
-
-  int get position();
-
-  int get totalSize();
-}