Introduce Position::inDocument()

Source/core/editing/MoveSelectionCommand.cpp

 /*
  * Copyright (C) 2005, 2006 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 44 matching lines @@
         if (selectionStart.anchorType() == Position::PositionIsOffsetInAnchor && selectionStart.containerNode() == pos.containerNode())
             pos.moveToOffset(pos.offsetInContainerNode() + selectionStart.offsetInContainerNode());
     }
 
     deleteSelection(m_smartDelete);
 
     // If the node for the destination has been removed as a result of the deletion,
     // set the destination to the ending point after the deletion.
     // Fixes: <rdar://problem/3910425> REGRESSION (Mail): Crash in ReplaceSelectionCommand;
     //        selection is empty, leading to null deref
-    if (!pos.anchorNode()->inDocument())
+    if (!pos.inDocument())
         pos = endingSelection().start();
 
     cleanupAfterDeletion(pos);
 
     setEndingSelection(VisibleSelection(pos, endingSelection().affinity(), endingSelection().isDirectional()));
-    if (!pos.anchorNode()->inDocument()) {
+    if (!pos.inDocument()) {
         // Document was modified out from under us.
         return;
     }
     ReplaceSelectionCommand::CommandOptions options = ReplaceSelectionCommand::SelectReplacement | ReplaceSelectionCommand::PreventNesting;
     if (m_smartInsert)
         options |= ReplaceSelectionCommand::SmartReplace;
     applyCommandToComposite(ReplaceSelectionCommand::create(document(), m_fragment, options));
 }
 
 EditAction MoveSelectionCommand::editingAction() const
 {
     return EditActionDrag;
 }
 
 } // namespace WebCore