Minor cleanup to RenderLayerScrollableArea::setNeedsCompositedScrolling.

Source/core/rendering/RenderLayerScrollableArea.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 203 matching lines @@
     void updateResizerAreaSet();
     void updateResizerStyle();
     void drawPlatformResizerImage(GraphicsContext*, IntRect resizerCornerRect);
 
     RenderLayer* layer() const;
 
     void updateScrollableAreaSet(bool hasOverflow);
 
     void updateCompositingLayersAfterScroll();
     virtual void updateNeedsCompositedScrolling() OVERRIDE;
-    bool setNeedsCompositedScrolling(bool);
+    void setNeedsCompositedScrolling(bool needsCompositedScrolling) { m_needsCompositedScrolling = needsCompositedScrolling; }
 
     void setForceNeedsCompositedScrolling(ForceNeedsCompositedScrollingMode);
 
     RenderBox* m_box;
 
     // Keeps track of whether the layer is currently resizing, so events can cause resizing to start and stop.
     unsigned m_inResizeMode : 1;
 
     unsigned m_scrollDimensionsDirty : 1;
     unsigned m_inOverflowRelayout : 1;
@@ skipping 17 matching lines @@
     // Renderers to hold our custom scroll corner.
     RenderScrollbarPart* m_scrollCorner;
 
     // Renderers to hold our custom resizer.
     RenderScrollbarPart* m_resizer;
 };
 
 } // Namespace WebCore
 
 #endif // RenderLayerScrollableArea_h