Add constructors to all the event classes.

client/html/generated/src/wrapping/_ProgressEventWrappingImplementation.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.
-
-// WARNING: Do not edit - generated code.
-
-class ProgressEventWrappingImplementation extends EventWrappingImplementation implements ProgressEvent {
-  ProgressEventWrappingImplementation._wrap(ptr) : super._wrap(ptr) {}
-
-  bool get lengthComputable() { return _ptr.lengthComputable; }
-
-  int get loaded() { return _ptr.loaded; }
-
-  int get total() { return _ptr.total; }
-
-  void initProgressEvent(String typeArg, bool canBubbleArg, bool cancelableArg, bool lengthComputableArg, int loadedArg, int totalArg) {
-    _ptr.initProgressEvent(typeArg, canBubbleArg, cancelableArg, lengthComputableArg, loadedArg, totalArg);
-    return;
-  }
-}