Remove stale files from lib/html/src.

lib/html/src/TouchEventWrappingImplementation.dart

-// 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.
-
-class TouchEventWrappingImplementation extends UIEventWrappingImplementation implements TouchEvent {
-  TouchEventWrappingImplementation._wrap(ptr) : super._wrap(ptr);
-
-  factory TouchEventWrappingImplementation(TouchList touches, TouchList targetTouches,
-      TouchList changedTouches, String type, Window view, int screenX,
-      int screenY, int clientX, int clientY, [bool ctrlKey = false,
-      bool altKey = false, bool shiftKey = false, bool metaKey = false]) {
-    final e = dom.document.createEvent("TouchEvent");
-    e.initTouchEvent(LevelDom.unwrap(touches), LevelDom.unwrap(targetTouches),
-        LevelDom.unwrap(changedTouches), type, LevelDom.unwrap(view), screenX,
-        screenY, clientX, clientY, ctrlKey, altKey, shiftKey, metaKey);
-    return LevelDom.wrapTouchEvent(e);
-  }
-
-  bool get altKey() => _ptr.altKey;
-
-  TouchList get changedTouches() => LevelDom.wrapTouchList(_ptr.changedTouches);
-
-  bool get ctrlKey() => _ptr.ctrlKey;
-
-  bool get metaKey() => _ptr.metaKey;
-
-  bool get shiftKey() => _ptr.shiftKey;
-
-  TouchList get targetTouches() => LevelDom.wrapTouchList(_ptr.targetTouches);
-
-  TouchList get touches() => LevelDom.wrapTouchList(_ptr.touches);
-}