Use tighter typing in editing: FormatBlockCommand / FrameSelection

Source/core/editing/FrameSelection.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple 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 74 matching lines @@
         return static_cast<EUserTriggered>(options & UserTriggered);
     }
 
     enum DirectoinalOption {
         NonDirectional,
         Directional
     };
 
     Element* rootEditableElement() const { return m_selection.rootEditableElement(); }
     Element* rootEditableElementOrDocumentElement() const;
-    Node* rootEditableElementOrTreeScopeRootNode() const;
+    ContainerNode* rootEditableElementOrTreeScopeRootNode() const;
 
     bool hasEditableStyle() const { return m_selection.hasEditableStyle(); }
     bool isContentEditable() const { return m_selection.isContentEditable(); }
     bool isContentRichlyEditable() const { return m_selection.isContentRichlyEditable(); }
 
     void moveTo(const VisiblePosition&, EUserTriggered = NotUserTriggered, CursorAlignOnScroll = AlignCursorOnScrollIfNeeded);
     void moveTo(const VisiblePosition&, const VisiblePosition&, EUserTriggered = NotUserTriggered);
     void moveTo(const Position&, EAffinity, EUserTriggered = NotUserTriggered);
 
     const VisibleSelection& selection() const { return m_selection; }
@@ skipping 202 matching lines @@
 }
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const blink::FrameSelection&);
 void showTree(const blink::FrameSelection*);
 #endif
 
 #endif // FrameSelection_h