Use refs for non-null GraphicsContext, Scrollbar, etc. in scrollbar related code

third_party/WebKit/Source/core/css/SelectorChecker.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 1142 matching lines @@
     case CSSSelector::PseudoDecrement:
         return part == BackButtonStartPart || part == BackButtonEndPart || part == BackTrackPart;
     case CSSSelector::PseudoIncrement:
         return part == ForwardButtonStartPart || part == ForwardButtonEndPart || part == ForwardTrackPart;
     case CSSSelector::PseudoStart:
         return part == BackButtonStartPart || part == ForwardButtonStartPart || part == BackTrackPart;
     case CSSSelector::PseudoEnd:
         return part == BackButtonEndPart || part == ForwardButtonEndPart || part == ForwardTrackPart;
     case CSSSelector::PseudoDoubleButton:
         {
-            ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme()->buttonsPlacement();
+            ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme().buttonsPlacement();
             if (part == BackButtonStartPart || part == ForwardButtonStartPart || part == BackTrackPart)
                 return buttonsPlacement == ScrollbarButtonsPlacementDoubleStart || buttonsPlacement == ScrollbarButtonsPlacementDoubleBoth;
             if (part == BackButtonEndPart || part == ForwardButtonEndPart || part == ForwardTrackPart)
                 return buttonsPlacement == ScrollbarButtonsPlacementDoubleEnd || buttonsPlacement == ScrollbarButtonsPlacementDoubleBoth;
             return false;
         }
     case CSSSelector::PseudoSingleButton:
         {
-            ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme()->buttonsPlacement();
+            ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme().buttonsPlacement();
             if (part == BackButtonStartPart || part == ForwardButtonEndPart || part == BackTrackPart || part == ForwardTrackPart)
                 return buttonsPlacement == ScrollbarButtonsPlacementSingle;
             return false;
         }
     case CSSSelector::PseudoNoButton:
         {
-            ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme()->buttonsPlacement();
+            ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme().buttonsPlacement();
             if (part == BackTrackPart)
                 return buttonsPlacement == ScrollbarButtonsPlacementNone || buttonsPlacement == ScrollbarButtonsPlacementDoubleEnd;
             if (part == ForwardTrackPart)
                 return buttonsPlacement == ScrollbarButtonsPlacementNone || buttonsPlacement == ScrollbarButtonsPlacementDoubleStart;
             return false;
         }
     case CSSSelector::PseudoCornerPresent:
         return scrollbar->scrollableArea() && scrollbar->scrollableArea()->isScrollCornerVisible();
     default:
         return false;
     }
 }
 
 bool SelectorChecker::matchesFocusPseudoClass(const Element& element)
 {
     if (InspectorInstrumentation::forcePseudoState(const_cast<Element*>(&element), CSSSelector::PseudoFocus))
         return true;
     return element.focused() && isFrameFocused(element);
 }
 
 }