Add constructors to all the event classes.

client/html/src/BeforeLoadEvent.dart

Index: client/html/src/BeforeLoadEvent.dart
diff --git a/client/html/generated/src/interface/BeforeLoadEvent.dart b/client/html/src/BeforeLoadEvent.dart
similarity index 58%
rename from client/html/generated/src/interface/BeforeLoadEvent.dart
rename to client/html/src/BeforeLoadEvent.dart
index 8d1f5bda63cc6a4abf71932efe7825425589aa81..4878e77f5eba03adb2e8175fdcf4140b2fe07867 100644
--- a/client/html/generated/src/interface/BeforeLoadEvent.dart
+++ b/client/html/src/BeforeLoadEvent.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 BeforeLoadEvent extends Event factory BeforeLoadEventWrappingImplementation {
 
-interface BeforeLoadEvent extends Event {
+  BeforeLoadEvent(String type, String url, [bool canBubble, bool cancelable]);
 
   String get url();
-
-  void initBeforeLoadEvent(String type, bool canBubble, bool cancelable, String url);
 }