Add constructors to all the event classes.

client/html/src/MutationEvent.dart

Index: client/html/src/MutationEvent.dart
diff --git a/client/html/generated/src/interface/MutationEvent.dart b/client/html/src/MutationEvent.dart
similarity index 65%
rename from client/html/generated/src/interface/MutationEvent.dart
rename to client/html/src/MutationEvent.dart
index 685c2abb9851ef94f487f0c399a97064a8844866..713e26aa52534cb1d993271b1ae7864c09ebbe5d 100644
--- a/client/html/generated/src/interface/MutationEvent.dart
+++ b/client/html/src/MutationEvent.dart
@@ -2,9 +2,11 @@
 // 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 MutationEvent extends Event factory MutationEventWrappingImplementation {
 
-interface MutationEvent extends Event {
+  MutationEvent(String type, Node relatedNode, String prevValue,
+      String newValue, String attrName, int attrChange, [bool canBubble,
+      bool cancelable]);
 
   static final int ADDITION = 2;
 
@@ -21,6 +23,4 @@ interface MutationEvent extends Event {
   String get prevValue();
 
   Node get relatedNode();
-
-  void initMutationEvent(String type, bool canBubble, bool cancelable, Node relatedNode, String prevValue, String newValue, String attrName, int attrChange);
 }