Remove Overlay Scrollbar if not scrollable along the axis

Source/core/rendering/RenderLayerScrollableArea.cpp

Index: Source/core/rendering/RenderLayerScrollableArea.cpp
diff --git a/Source/core/rendering/RenderLayerScrollableArea.cpp b/Source/core/rendering/RenderLayerScrollableArea.cpp
index 69884479df62801e90c339d3544f19e4d144ce19..5a085bee6c4e903d6a0a7a4a3f99ffa8e8c29a1f 100644
--- a/Source/core/rendering/RenderLayerScrollableArea.cpp
+++ b/Source/core/rendering/RenderLayerScrollableArea.cpp
@@ -611,12 +611,17 @@ void RenderLayerScrollableArea::updateAfterLayout()
         DisableCompositingQueryAsserts disabler;
 
         // overflow:scroll should just enable/disable.
-        if (box().style()->overflowX() == OSCROLL)
+        if (box().style()->overflowX() == OSCROLL && horizontalScrollbar())

[MuVen, 2014/10/13 15:45:01]

This checks fixes webkit_unit_tests crashes on android_dbg_tests_recipe.

             horizontalScrollbar()->setEnabled(hasHorizontalOverflow);
-        if (box().style()->overflowY() == OSCROLL)
+        if (box().style()->overflowY() == OSCROLL && verticalScrollbar())
             verticalScrollbar()->setEnabled(hasVerticalOverflow);
     }
-
+    if (hasOverlayScrollbars()) {
+        if (!scrollSize(HorizontalScrollbar))
+            setHasHorizontalScrollbar(false);
+        if (!scrollSize(VerticalScrollbar))
+            setHasVerticalScrollbar(false);
+    }
     // overflow:auto may need to lay out again if scrollbars got added/removed.
     bool autoHorizontalScrollBarChanged = box().hasAutoHorizontalScrollbar() && (hasHorizontalScrollbar() != hasHorizontalOverflow);
     bool autoVerticalScrollBarChanged = box().hasAutoVerticalScrollbar() && (hasVerticalScrollbar() != hasVerticalOverflow);