Refactoring: Extract DocumentInit for capture Document construction parameter.

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..ebcb33eee1ea8cc0caf6ba49332853160b660702 100644
--- a/Source/core/xml/XMLHttpRequest.cpp
+++ b/Source/core/xml/XMLHttpRequest.cpp
@@ -244,9 +244,9 @@ Document* XMLHttpRequest::responseXML(ExceptionCode& ec)
             m_responseDocument = 0;
         } else {
             if (isHTML)
-                m_responseDocument = HTMLDocument::create(0, m_url);
+                m_responseDocument = HTMLDocument::create(DocumentInitializer(m_url));
             else
-                m_responseDocument = Document::create(0, m_url);
+                m_responseDocument = Document::create(DocumentInitializer(m_url));
             // FIXME: Set Last-Modified.
             m_responseDocument->setContent(m_responseText.flattenToString());
             m_responseDocument->setSecurityOrigin(securityOrigin());