Delete some noop and dead scrollbar code.

sky/engine/platform/scroll/Scrollbar.h

Index: sky/engine/platform/scroll/Scrollbar.h
diff --git a/sky/engine/platform/scroll/Scrollbar.h b/sky/engine/platform/scroll/Scrollbar.h
index 8fcf3c7bed5405d08338e937f9534169d4e190dd..5936913d74ae72e4eabca10fc1380dbc0e0bece4 100644
--- a/sky/engine/platform/scroll/Scrollbar.h
+++ b/sky/engine/platform/scroll/Scrollbar.h
@@ -47,7 +47,6 @@ public:
 
     virtual ~Scrollbar();
 
-    ScrollbarOverlayStyle scrollbarOverlayStyle() const;
     bool isScrollableAreaActive() const;
 
     ScrollbarOrientation orientation() const { return m_orientation; }
@@ -59,9 +58,6 @@ public:
     int totalSize() const { return m_totalSize; }
     int maximum() const { return m_totalSize - m_visibleSize; }
 
-    bool enabled() const { return m_enabled; }
-    void setEnabled(bool);
-
     // Called by the ScrollableArea when the scroll offset changes.
     void offsetDidChange();
 
@@ -152,8 +148,6 @@ protected:
     float m_scrollPos;
     int m_documentDragPos;
 
-    bool m_enabled;
-
     Timer<Scrollbar> m_scrollTimer;
     bool m_overlapsResizer;