Pass scroll bar placement as an enum instead of std::string

Source/core/css/SelectorChecker.cpp

Index: Source/core/css/SelectorChecker.cpp
diff --git a/Source/core/css/SelectorChecker.cpp b/Source/core/css/SelectorChecker.cpp
index d711fb9b52329d73c29794d06908c5ceb468f098..bfe86da711d080d01dfafe40203687a3d6bc861e 100644
--- a/Source/core/css/SelectorChecker.cpp
+++ b/Source/core/css/SelectorChecker.cpp
@@ -1148,25 +1148,25 @@ bool SelectorChecker::checkScrollbarPseudoClass(const SelectorCheckingContext& c
         {
             ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme()->buttonsPlacement();
             if (part == BackButtonStartPart || part == ForwardButtonStartPart || part == BackTrackPart)
-                return buttonsPlacement == ScrollbarButtonsDoubleStart || buttonsPlacement == ScrollbarButtonsDoubleBoth;
+                return buttonsPlacement == ScrollbarButtonsPlacementDoubleStart || buttonsPlacement == ScrollbarButtonsPlacementDoubleBoth;
             if (part == BackButtonEndPart || part == ForwardButtonEndPart || part == ForwardTrackPart)
-                return buttonsPlacement == ScrollbarButtonsDoubleEnd || buttonsPlacement == ScrollbarButtonsDoubleBoth;
+                return buttonsPlacement == ScrollbarButtonsPlacementDoubleEnd || buttonsPlacement == ScrollbarButtonsPlacementDoubleBoth;
             return false;
         }
     case CSSSelector::PseudoSingleButton:
         {
             ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme()->buttonsPlacement();
             if (part == BackButtonStartPart || part == ForwardButtonEndPart || part == BackTrackPart || part == ForwardTrackPart)
-                return buttonsPlacement == ScrollbarButtonsSingle;
+                return buttonsPlacement == ScrollbarButtonsPlacementSingle;
             return false;
         }
     case CSSSelector::PseudoNoButton:
         {
             ScrollbarButtonsPlacement buttonsPlacement = scrollbar->theme()->buttonsPlacement();
             if (part == BackTrackPart)
-                return buttonsPlacement == ScrollbarButtonsNone || buttonsPlacement == ScrollbarButtonsDoubleEnd;
+                return buttonsPlacement == ScrollbarButtonsPlacementNone || buttonsPlacement == ScrollbarButtonsPlacementDoubleEnd;
             if (part == ForwardTrackPart)
-                return buttonsPlacement == ScrollbarButtonsNone || buttonsPlacement == ScrollbarButtonsDoubleStart;
+                return buttonsPlacement == ScrollbarButtonsPlacementNone || buttonsPlacement == ScrollbarButtonsPlacementDoubleStart;
             return false;
         }
     case CSSSelector::PseudoCornerPresent: