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

Source/core/editing/DeleteSelectionCommand.cpp

 /*
  * Copyright (C) 2005 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 68 matching lines @@
     , m_startsAtEmptyLine(false)
     , m_sanitizeMarkup(sanitizeMarkup)
     , m_startBlock(0)
     , m_endBlock(0)
     , m_typingStyle(0)
     , m_deleteIntoBlockquoteStyle(0)
 {
 }
 
 DeleteSelectionCommand::DeleteSelectionCommand(const VisibleSelection& selection, bool smartDelete, bool mergeBlocksAfterDelete, bool replace, bool expandForSpecialElements, bool sanitizeMarkup)
-    : CompositeEditCommand(selection.start().anchorNode()->document())
+    : CompositeEditCommand(&selection.start().anchorNode()->document())
     , m_hasSelectionToDelete(true)
     , m_smartDelete(smartDelete)
     , m_mergeBlocksAfterDelete(mergeBlocksAfterDelete)
     , m_needPlaceholder(false)
     , m_replace(replace)
     , m_expandForSpecialElements(expandForSpecialElements)
     , m_pruneStartBlockIfNecessary(false)
     , m_startsAtEmptyLine(false)
     , m_sanitizeMarkup(sanitizeMarkup)
     , m_selectionToDelete(selection)
@@ skipping 751 matching lines @@
 
 // Normally deletion doesn't preserve the typing style that was present before it.  For example,
 // type a character, Bold, then delete the character and start typing.  The Bold typing style shouldn't
 // stick around.  Deletion should preserve a typing style that *it* sets, however.
 bool DeleteSelectionCommand::preservesTypingStyle() const
 {
     return m_typingStyle;
 }
 
 } // namespace WebCore