Cleanup LayoutTextControl and its subclasses.

Source/core/layout/LayoutTextControlSingleLine.h

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 49 matching lines @@
 
     // Subclassed to forward to our inner div.
     LayoutUnit scrollLeft() const final;
     LayoutUnit scrollTop() const final;
     LayoutUnit scrollWidth() const final;
     LayoutUnit scrollHeight() const final;
     void setScrollLeft(LayoutUnit) final;
     void setScrollTop(LayoutUnit) final;
 
     int textBlockWidth() const;
-    float getAvgCharWidth(AtomicString family) final;
+    float getAvgCharWidth(const AtomicString& family) const final;
     LayoutUnit preferredContentLogicalWidth(float charWidth) const final;
     LayoutUnit computeControlLogicalHeight(LayoutUnit lineHeight, LayoutUnit nonContentHeight) const override;
 
     void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) final;
 
     bool textShouldBeTruncated() const;
 
     HTMLElement* innerSpinButtonElement() const;
 
     bool m_shouldDrawCapsLockIndicator;
@@ skipping 15 matching lines @@
         return orientation == HorizontalScrollbar;
     }
     bool scrollsOverflowX() const override { return hasOverflowClip(); }
     bool scrollsOverflowY() const override { return false; }
     bool hasLineIfEmpty() const override { return true; }
 };
 
 }
 
 #endif