Fix for RenderListBox not showing vertical scrollbar with overlay-scrollbar enabled.

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 c2d226076b2c2fd3d8101ddd11dbec7d2ebe8c15..44147b0df08a94a11ae1bd62c97b70283c551d4a 100644
--- a/Source/core/rendering/RenderListBox.cpp
+++ b/Source/core/rendering/RenderListBox.cpp
@@ -227,9 +227,7 @@ void RenderListBox::scrollToRevealSelection()
 
 void RenderListBox::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
 {
-    maxLogicalWidth = m_optionsWidth + 2 * optionsSpacingHorizontal;
-    if (m_vBar)
-        maxLogicalWidth += verticalScrollbarWidth();
+    maxLogicalWidth = m_optionsWidth + 2 * optionsSpacingHorizontal + verticalScrollbarWidth();
     if (!style()->width().isPercent())
         minLogicalWidth = maxLogicalWidth;
 }
@@ -389,7 +387,7 @@ int RenderListBox::scrollbarLeft() const
     if (style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft())
         scrollbarLeft = borderLeft();
     else
-        scrollbarLeft = width() - borderRight() - verticalScrollbarWidth();
+        scrollbarLeft = width() - borderRight() - (m_vBar ? m_vBar->width() : 0);

[tkent, 2014/06/18 04:52:22]

Why isn't this verticalScrollbarWidth()?

[pals, 2014/06/18 05:11:44]

As we see, in case of overlayscrollbars, verticalScrollbarWidth() return 0, so,
in case of "dir: ltr" the scrollbar will be placed at width() [assuming
borderRight() is 0] which at the edge/outside of the Box. So, we will not be
able to see the scrollbar. 

[tkent, 2014/06/18 05:14:42]

Ah, I see. This function calculates the position of scrollbar.
Thanks.

     return scrollbarLeft;
 }
 
@@ -398,7 +396,7 @@ void RenderListBox::paintScrollbar(PaintInfo& paintInfo, const LayoutPoint& pain
     if (m_vBar) {
         IntRect scrollRect = pixelSnappedIntRect(paintOffset.x() + scrollbarLeft(),
             paintOffset.y() + borderTop(),
-            verticalScrollbarWidth(),
+            m_vBar->width(),
             height() - (borderTop() + borderBottom()));
         m_vBar->setFrameRect(scrollRect);
         m_vBar->paint(paintInfo.context, paintInfo.rect);