Make first-letter style to work with editing

Source/core/editing/FrameSelection.h

Index: Source/core/editing/FrameSelection.h
diff --git a/Source/core/editing/FrameSelection.h b/Source/core/editing/FrameSelection.h
index 8fc4642f9e30cb78b1fdc30323d3c0fdbbfc5835..cb0f2b3617955baad40a64a405b5aac188ddc32f 100644
--- a/Source/core/editing/FrameSelection.h
+++ b/Source/core/editing/FrameSelection.h
@@ -61,12 +61,12 @@ protected:
     enum CaretVisibility { Visible, Hidden };
     explicit CaretBase(CaretVisibility = Hidden);
 
-    void invalidateCaretRect(Node*, bool caretRectChanged = false);
+    void invalidateCaretRect(const Position&, bool caretRectChanged = false);
     void clearCaretRect();
     bool updateCaretRect(Document*, const VisiblePosition& caretPosition);
-    IntRect absoluteBoundsForLocalRect(Node*, const LayoutRect&) const;
+    IntRect absoluteBoundsForLocalRect(const Position&, const LayoutRect&) const;
     bool shouldRepaintCaret(const RenderView*, bool isContentEditable) const;
-    void paintCaret(Node*, GraphicsContext*, const LayoutPoint&, const LayoutRect& clipRect) const;
+    void paintCaret(const Position&, GraphicsContext*, const LayoutPoint&, const LayoutRect& clipRect) const;
 
     const LayoutRect& localCaretRectWithoutUpdate() const { return m_caretLocalRect; }
 
@@ -306,7 +306,7 @@ private:
     VisiblePosition m_originalBase; // Used to store base before the adjustment at bidi boundary
     TextGranularity m_granularity;
 
-    RefPtr<Node> m_previousCaretNode; // The last node which painted the caret. Retained for clearing the old caret when it moves.
+    Position m_previousCaretPosition; // The last position which painted the caret. Retained for clearing the old caret when it moves.
 
     RefPtr<EditingStyle> m_typingStyle;