Have Node::document() return a reference instead of a pointer

Source/web/ValidationMessageClientImpl.cpp

Index: Source/web/ValidationMessageClientImpl.cpp
diff --git a/Source/web/ValidationMessageClientImpl.cpp b/Source/web/ValidationMessageClientImpl.cpp
index 6c7c1557363e3492aacda7c426a95a469443090f..6a09e9d2783d6102d3858839f9eab8d77e2df9d5 100644
--- a/Source/web/ValidationMessageClientImpl.cpp
+++ b/Source/web/ValidationMessageClientImpl.cpp
@@ -64,7 +64,7 @@ ValidationMessageClientImpl::~ValidationMessageClientImpl()
 
 FrameView* ValidationMessageClientImpl::currentView()
 {
-    return m_currentAnchor->document()->view();
+    return m_currentAnchor->document().view();
 }
 
 void ValidationMessageClientImpl::showValidationMessage(const Element& anchor, const String& message)
@@ -114,7 +114,7 @@ bool ValidationMessageClientImpl::isValidationMessageVisible(const Element& anch
 
 void ValidationMessageClientImpl::documentDetached(const Document& document)
 {
-    if (m_currentAnchor && m_currentAnchor->document() == &document)
+    if (m_currentAnchor && &m_currentAnchor->document() == &document)
         hideValidationMessage(*m_currentAnchor);
 }