Use tighter typing in editing: VisiblePosition & VisibleSelection

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 782 matching lines @@
         || (downstreamEnd.containerNode()->isTextNode() && downstreamEnd.containerNode()->parentNode() == downstreamEnd.containerNode()->rootEditableElement());
     bool lineBreakAtEndOfSelectionToDelete = lineBreakExistsAtVisiblePosition(m_selectionToDelete.visibleEnd());
     m_needPlaceholder = !rootWillStayOpenWithoutPlaceholder
         && isStartOfParagraph(m_selectionToDelete.visibleStart(), CanCrossEditingBoundary)
         && isEndOfParagraph(m_selectionToDelete.visibleEnd(), CanCrossEditingBoundary)
         && !lineBreakAtEndOfSelectionToDelete;
     if (m_needPlaceholder) {
         // Don't need a placeholder when deleting a selection that starts just before a table
         // and ends inside it (we do need placeholders to hold open empty cells, but that's
         // handled elsewhere).
-        if (Node* table = isLastPositionBeforeTable(m_selectionToDelete.visibleStart()))
+        if (Element* table = isLastPositionBeforeTable(m_selectionToDelete.visibleStart()))
             if (m_selectionToDelete.end().deprecatedNode()->isDescendantOf(table))
                 m_needPlaceholder = false;
     }
 
 
     // set up our state
     initializePositionData();
 
     bool lineBreakBeforeStart = lineBreakExistsAtVisiblePosition(VisiblePosition(m_upstreamStart).previous());
 
@@ skipping 75 matching lines @@
     visitor->trace(m_deleteIntoBlockquoteStyle);
     visitor->trace(m_startRoot);
     visitor->trace(m_endRoot);
     visitor->trace(m_startTableRow);
     visitor->trace(m_endTableRow);
     visitor->trace(m_temporaryPlaceholder);
     CompositeEditCommand::trace(visitor);
 }
 
 } // namespace blink