Share Custom Element registration contexts between related documents.

Source/core/xml/XMLHttpRequest.cpp

Index: Source/core/xml/XMLHttpRequest.cpp
diff --git a/Source/core/xml/XMLHttpRequest.cpp b/Source/core/xml/XMLHttpRequest.cpp
index d1a700e6e95a61f32adf0d7b5d7298cfbc4e15dd..4ba5117f0b0554c4a4b33a1232b3ee44f02c5276 100644
--- a/Source/core/xml/XMLHttpRequest.cpp
+++ b/Source/core/xml/XMLHttpRequest.cpp
@@ -30,6 +30,7 @@
 #include <wtf/text/CString.h>
 #include <wtf/UnusedParam.h>
 #include "core/dom/ContextFeatures.h"
+#include "core/dom/CustomElementRegistrationContextualizer.h"
 #include "core/dom/DOMImplementation.h"
 #include "core/dom/Event.h"
 #include "core/dom/EventListener.h"
@@ -251,6 +252,7 @@ Document* XMLHttpRequest::responseXML(ExceptionCode& ec)
             m_responseDocument->setContent(m_responseText.flattenToString());
             m_responseDocument->setSecurityOrigin(securityOrigin());
             m_responseDocument->setContextFeatures(document()->contextFeatures());
+            CustomElementRegistrationContextualizer::didCreateDocument(CustomElementRegistrationContextualizer::XHR_responseXML, m_responseDocument.get());
             if (!m_responseDocument->wellFormed())
                 m_responseDocument = 0;
         }