Position overflow controls during layout.

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 98b9b508ba98d543cfa03b82abb4550953de877b..b6fe35955b6bf69d78f98fb494835262a12b1c35 100644
--- a/Source/core/rendering/RenderLayerScrollableArea.cpp
+++ b/Source/core/rendering/RenderLayerScrollableArea.cpp
@@ -650,7 +650,13 @@ void RenderLayerScrollableArea::updateAfterLayout()
         }
     }
 
-    updateScrollableAreaSet(hasScrollableHorizontalOverflow() || hasScrollableVerticalOverflow());
+    bool hasOverflow = hasScrollableHorizontalOverflow() || hasScrollableVerticalOverflow();
+    updateScrollableAreaSet(hasOverflow);
+
+    if (hasOverflow) {
+        DisableCompositingQueryAsserts disabler;
+        positionOverflowControls(IntSize());
+    }
 }
 
 bool RenderLayerScrollableArea::hasHorizontalOverflow() const