First part of work to move V8 binding integrity off of vtables.

Source/WebCore/Modules/encryptedmedia/MediaKeyMessageEvent.cpp

Index: Source/WebCore/Modules/encryptedmedia/MediaKeyMessageEvent.cpp
diff --git a/Source/WebCore/Modules/encryptedmedia/MediaKeyMessageEvent.cpp b/Source/WebCore/Modules/encryptedmedia/MediaKeyMessageEvent.cpp
index 4a9c843a6521f9b1c7f2d9bbbf2036c43e7aca79..48f6d36405d2fab27ce1b048fa56f43fa5da17e8 100644
--- a/Source/WebCore/Modules/encryptedmedia/MediaKeyMessageEvent.cpp
+++ b/Source/WebCore/Modules/encryptedmedia/MediaKeyMessageEvent.cpp
@@ -36,10 +36,12 @@ namespace WebCore {
 
 MediaKeyMessageEventInit::MediaKeyMessageEventInit()
 {
+    ScriptWrappable::init(this);
 }
 
 MediaKeyMessageEvent::MediaKeyMessageEvent()
 {
+    ScriptWrappable::init(this);
 }
 
 MediaKeyMessageEvent::MediaKeyMessageEvent(const AtomicString& type, const MediaKeyMessageEventInit& initializer)
@@ -47,6 +49,7 @@ MediaKeyMessageEvent::MediaKeyMessageEvent(const AtomicString& type, const Media
     , m_message(initializer.message)
     , m_destinationURL(initializer.destinationURL)
 {
+    ScritpWrappable::init(this);
 }
 
 MediaKeyMessageEvent::~MediaKeyMessageEvent()