--- a/encrypted-media/encrypted-media.html	Tue Jun 24 13:31:00 2014 -0700
+++ b/encrypted-media/encrypted-media.html	Tue Jun 24 13:38:43 2014 -0700
@@ -977,8 +977,8 @@
 };
 
 dictionary <dfn id="dom-mediakeyneededeventinit">MediaKeyNeededEventInit</dfn> : <a href="http://www.w3.org/TR/dom/#eventinit">EventInit</a> {
-  DOMString <a href="#dom-initdatatype">initDataType</a>;
-  ArrayBuffer? <a href="#dom-initdata">initData</a>;
+  DOMString <a href="#dom-initdatatype">initDataType</a> = "";
+  ArrayBuffer? <a href="#dom-initdata">initData</a> = null;
 };
 </pre>
 
@@ -986,12 +986,12 @@
 [Constructor(DOMString type, optional <a href="#dom-mediakeymessageeventinit">MediaKeyMessageEventInit</a> eventInitDict)]
 interface <dfn id="dom-mediakeymessageevent">MediaKeyMessageEvent</dfn> : <a href="http://www.w3.org/TR/dom/#event">Event</a> {
   readonly attribute ArrayBuffer <a href="#dom-message">message</a>;
-  readonly attribute DOMString? <a href="#dom-destinationurl">destinationURL</a>;
+  readonly attribute DOMString? <a href="#dom-destinationurl">destinationURL</a> = null;
 };
 
 dictionary <dfn id="dom-mediakeymessageeventinit">MediaKeyMessageEventInit</dfn> : <a href="http://www.w3.org/TR/dom/#eventinit">EventInit</a> {
-  ArrayBuffer <a href="#dom-message">message</a>;
-  DOMString? <a href="#dom-destinationurl">destinationURL</a>;
+  ArrayBuffer <a href="#dom-message">message</a> = ArrayBuffer(); 
+  DOMString? <a href="#dom-destinationurl">destinationURL</a> = null;
 };
 </pre>
 

--- a/encrypted-media/encrypted-media.xml	Tue Jun 24 13:31:00 2014 -0700
+++ b/encrypted-media/encrypted-media.xml	Tue Jun 24 13:38:43 2014 -0700
@@ -919,8 +919,8 @@
 };
 
 dictionary <precodedfn>MediaKeyNeededEventInit</precodedfn> : <dom4ref name="eventinit">EventInit</dom4ref> {
-  DOMString <precoderef>initDataType</precoderef>;
-  ArrayBuffer? <precoderef>initData</precoderef>;
+  DOMString <precoderef>initDataType</precoderef> = "";
+  ArrayBuffer? <precoderef>initData</precoderef> = null;
 };
 </pre>
 
@@ -928,12 +928,12 @@
 [Constructor(DOMString type, optional <precoderef>MediaKeyMessageEventInit</precoderef> eventInitDict)]
 interface <precodedfn>MediaKeyMessageEvent</precodedfn> : <dom4ref name="event">Event</dom4ref> {
   readonly attribute ArrayBuffer <precoderef>message</precoderef>;
-  readonly attribute DOMString? <precoderef>destinationURL</precoderef>;
+  readonly attribute DOMString? <precoderef>destinationURL</precoderef> = null;
 };
 
 dictionary <precodedfn>MediaKeyMessageEventInit</precodedfn> : <dom4ref name="eventinit">EventInit</dom4ref> {
-  ArrayBuffer <precoderef>message</precoderef>;
-  DOMString? <precoderef>destinationURL</precoderef>;
+  ArrayBuffer <precoderef>message</precoderef> = ArrayBuffer(); 
+  DOMString? <precoderef>destinationURL</precoderef> = null;
 };
 </pre>