Use high resolution markers when device scale factor > 1.5f

Source/core/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 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 3600 matching lines @@
     // the outline is painted in the background phase during composited scrolling.
     // If it were painted in the foreground phase, it would move with the scrolled
     // content. When not composited scrolling, the outline is painted in the
     // foreground phase. Since scrolled contents are moved by repainting in this
     // case, the outline won't get 'dragged along'.
     bool shouldPaintOutline = isSelfPaintingLayer && !isPaintingOverlayScrollbars
         && ((isPaintingScrollingContent && isPaintingCompositedBackground)
         || (!isPaintingScrollingContent && isPaintingCompositedForeground));
     bool shouldPaintContent = m_hasVisibleContent && isSelfPaintingLayer && !isPaintingOverlayScrollbars;
 
+    float deviceScaleFactor = WebCore::deviceScaleFactor(renderer()->frame());
+    context->setUseHighResMarkers(deviceScaleFactor > 1.5f);
+
     GraphicsContext* transparencyLayerContext = context;
     
     if (localPaintFlags & PaintLayerPaintingRootBackgroundOnly && !renderer()->isRenderView() && !renderer()->isRoot())
         return;
 
     // Ensure our lists are up-to-date.
     updateLayerListsIfNeeded();
 
     LayoutPoint offsetFromRoot;
     convertToLayerCoords(paintingInfo.rootLayer, offsetFromRoot);
@@ skipping 2735 matching lines @@
     }
 }
 
 void showLayerTree(const WebCore::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif