Have Document::formController() return a reference

Source/core/dom/Document.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 422 matching lines @@
     void removedStyleSheet(StyleSheet*, RecalcStyleTime when = RecalcStyleDeferred, StyleResolverUpdateMode = FullStyleUpdate);
     void addedStyleSheet(StyleSheet*, RecalcStyleTime when = RecalcStyleDeferred) { styleResolverChanged(when); }
     void modifiedStyleSheet(StyleSheet*, RecalcStyleTime when = RecalcStyleDeferred, StyleResolverUpdateMode = FullStyleUpdate);
     void changedSelectorWatch() { styleResolverChanged(RecalcStyleDeferred); }
 
     void scheduleUseShadowTreeUpdate(SVGUseElement&);
     void unscheduleUseShadowTreeUpdate(SVGUseElement&);
 
     void evaluateMediaQueryList();
 
-    // Never returns 0.
-    FormController* formController();
+    FormController& formController();
     Vector<String> formElementsState() const;
     void setStateForNewFormElements(const Vector<String>&);
 
     FrameView* view() const; // can be null
     LocalFrame* frame() const { return m_frame; } // can be null
     FrameHost* frameHost() const; // can be null
     Page* page() const; // can be null
     Settings* settings() const; // can be null
 
     float devicePixelRatio() const;
@@ skipping 941 matching lines @@
 inline bool Node::isDocumentNode() const
 {
     return this == document();
 }
 
 Node* eventTargetNodeForDocument(Document*);
 
 } // namespace WebCore
 
 #endif // Document_h