Improve outline bounds estimation in InlinePainter

Source/core/paint/InlinePainter.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef InlinePainter_h
 #define InlinePainter_h
 
 #include "core/style/ComputedStyleConstants.h"
 
 namespace blink {
 
 class Color;
 class GraphicsContext;
 class LayoutPoint;
 class LayoutRect;
 struct PaintInfo;
 class LayoutInline;
 
 class InlinePainter {
 public:
     InlinePainter(LayoutInline& layoutInline) : m_layoutInline(layoutInline) { }
 
     void paint(const PaintInfo&, const LayoutPoint& paintOffset);
     void paintOutline(const PaintInfo&, const LayoutPoint& paintOffset);
 
 private:
+    LayoutRect outlinePaintRect(const LayoutPoint& paintOffset) const;
     void paintOutlineForLine(GraphicsContext*, const LayoutPoint&, const LayoutRect& prevLine, const LayoutRect& thisLine,
         const LayoutRect& nextLine, const Color);
     LayoutInline& m_layoutInline;
 };
 
 } // namespace blink
 
 #endif // InlinePainter_h