Add constructors to all the event classes.

client/html/src/MessageEvent.dart

Index: client/html/src/MessageEvent.dart
diff --git a/client/html/generated/src/interface/MessageEvent.dart b/client/html/src/MessageEvent.dart
similarity index 57%
rename from client/html/generated/src/interface/MessageEvent.dart
rename to client/html/src/MessageEvent.dart
index 50a41f236d6cb066405a19cdfd8f629b27aa9135..5df049728fb0bbdabd80954e59870ae9e0182636 100644
--- a/client/html/generated/src/interface/MessageEvent.dart
+++ b/client/html/src/MessageEvent.dart
@@ -2,9 +2,10 @@
 // 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 MessageEvent extends Event factory MessageEventWrappingImplementation {
 
-interface MessageEvent extends Event {
+  MessageEvent(String type, String data, String origin, String lastEventId,
+      Window source, [bool canBubble, bool cancelable, MessagePort port]);
 
   String get data();
 
@@ -15,6 +16,4 @@ interface MessageEvent extends Event {
   String get origin();
 
   Window get source();
-
-  void initMessageEvent(String typeArg, bool canBubbleArg, bool cancelableArg, String dataArg, String originArg, String lastEventIdArg, Window sourceArg, MessagePort messagePort);
 }