Add constructors to all the event classes.

client/html/src/CustomEvent.dart

Index: client/html/src/CustomEvent.dart
diff --git a/client/html/generated/src/interface/CustomEvent.dart b/client/html/src/CustomEvent.dart
similarity index 57%
rename from client/html/generated/src/interface/CustomEvent.dart
rename to client/html/src/CustomEvent.dart
index eb3705ec13c85ba3300fabd54c1f1c0be0562a60..1c444b594395703c84022c9694a253872b965db4 100644
--- a/client/html/generated/src/interface/CustomEvent.dart
+++ b/client/html/src/CustomEvent.dart
@@ -2,11 +2,9 @@
 // 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.
+interface CustomEvent extends Event factory CustomEventWrappingImplementation {
 
-interface CustomEvent extends Event {
+  CustomEvent(String type, [bool canBubble, bool cancelable, Object detail]);
 
   String get detail();
-
-  void initCustomEvent(String typeArg, bool canBubbleArg, bool cancelableArg, Object detailArg);
 }