Have DOMImplementation take the Document argument by reference

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index d507bf2a78af9110224ac5339df52ef7f4223299..c55efbd7ec6591c3e45ee5c6e5a6fb6537f34f69 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -645,7 +645,7 @@ void Document::setDoctype(PassRefPtr<DocumentType> docType)
 DOMImplementation* Document::implementation()
 {
     if (!m_implementation)
-        m_implementation = DOMImplementation::create(this);
+        m_implementation = DOMImplementation::create(*this);
     return m_implementation.get();
 }