Make sure we never pass a null Frame to Document::canNavigate()

Source/core/frame/Frame.h

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999-2001 Lars Knoll <knoll@kde.org>
  *                     1999-2001 Antti Koivisto <koivisto@kde.org>
  *                     2000-2001 Simon Hausmann <hausmann@kde.org>
  *                     2000-2001 Dirk Mueller <mueller@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
@@ skipping 124 matching lines @@
 inline HTMLFrameOwnerElement* Frame::ownerElement() const
 {
     return m_ownerElement;
 }
 
 inline FrameTree& Frame::tree() const
 {
     return m_treeNode;
 }
 
+// Allow equality comparisons of Frames by reference or pointer, interchangeably.

[eseidel, 2014/06/02 05:20:27]

Can we make this a macro?  Seems silly to have to type this out.

[Inactive, 2014/06/02 12:16:37]

Makes sense. We already duplicate this for several classes. Will do (likely in a
separate patch for clarity).

+inline bool operator==(const Frame& a, const Frame& b) { return &a == &b; }
+inline bool operator==(const Frame& a, const Frame* b) { return &a == b; }
+inline bool operator==(const Frame* a, const Frame& b) { return a == &b; }
+inline bool operator!=(const Frame& a, const Frame& b) { return !(a == b); }
+inline bool operator!=(const Frame& a, const Frame* b) { return !(a == b); }
+inline bool operator!=(const Frame* a, const Frame& b) { return !(a == b); }
+inline bool operator==(const PassRefPtr<Frame>& a, const Frame& b) { return a.get() == &b; }
+inline bool operator==(const Frame& a, const PassRefPtr<Frame>& b) { return &a == b.get(); }
+inline bool operator!=(const PassRefPtr<Frame>& a, const Frame& b) { return !(a == b); }
+inline bool operator!=(const Frame& a, const PassRefPtr<Frame>& b) { return !(a == b); }
+
 } // namespace WebCore
 
 #endif // Frame_h