Allow objects without scrollbars to be scrollable

Source/core/rendering/RenderListBox.cpp

Index: Source/core/rendering/RenderListBox.cpp
diff --git a/Source/core/rendering/RenderListBox.cpp b/Source/core/rendering/RenderListBox.cpp
index 6ebf5ef11adc88b1d929470a72ab6eb3e649c998..7ff31f489b7bc41a83257c33b7d57e651692be36 100644
--- a/Source/core/rendering/RenderListBox.cpp
+++ b/Source/core/rendering/RenderListBox.cpp
@@ -624,7 +624,7 @@ void RenderListBox::valueChanged(unsigned listIndex)
 
 int RenderListBox::scrollSize(ScrollbarOrientation orientation) const
 {
-    return ((orientation == VerticalScrollbar) && m_vBar) ? (m_vBar->totalSize() - m_vBar->visibleSize()) : 0;
+    return orientation == VerticalScrollbar ? (numItems() - numVisibleItems()) : 0;
 }
 
 int RenderListBox::scrollPosition(Scrollbar*) const
@@ -632,6 +632,13 @@ int RenderListBox::scrollPosition(Scrollbar*) const
     return m_indexOffset;
 }
 
+IntPoint RenderListBox::scrollPosition() const
+{
+    int x = 0;
+    int y = m_indexOffset;
+    return IntPoint(x, y);
+}
+
 void RenderListBox::setScrollOffset(const IntPoint& offset)
 {
     scrollTo(offset.y());