Allow objects without scrollbars to be scrollable

Source/core/rendering/RenderListBox.h

Index: Source/core/rendering/RenderListBox.h
diff --git a/Source/core/rendering/RenderListBox.h b/Source/core/rendering/RenderListBox.h
index 1b53fda3f2648a040a287cdeaa3f9a146ecdc34f..61d9673a776af988d192fac630042789a5214a32 100644
--- a/Source/core/rendering/RenderListBox.h
+++ b/Source/core/rendering/RenderListBox.h
@@ -104,6 +104,7 @@ private:
     // ScrollableArea interface.
     virtual int scrollSize(ScrollbarOrientation) const OVERRIDE;
     virtual int scrollPosition(Scrollbar*) const OVERRIDE;
+    virtual IntPoint scrollPosition() const OVERRIDE;
     virtual void setScrollOffset(const IntPoint&) OVERRIDE;
     virtual void invalidateScrollbarRect(Scrollbar*, const IntRect&) OVERRIDE;
     virtual bool isActive() const OVERRIDE;
@@ -122,6 +123,11 @@ private:
     virtual bool shouldSuspendScrollAnimations() const OVERRIDE;
     virtual bool scrollbarsCanBeActive() const OVERRIDE;
     virtual IntPoint maximumScrollPosition() const OVERRIDE;
+    virtual bool userInputScrollable(ScrollbarOrientation) const OVERRIDE;
+    virtual int lineStep(ScrollbarOrientation) const;
+    virtual int pageStep(ScrollbarOrientation) const;
+    virtual float pixelStep(ScrollbarOrientation) const;
+
 
     virtual ScrollableArea* enclosingScrollableArea() const OVERRIDE;
     virtual IntRect scrollableAreaBoundingBox() const OVERRIDE;