The element's offset isn't relevant when comparing its dimensions with that of its overflow

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@gmail.com>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 568 matching lines @@
     return m_overflowRect.width();
 }
 
 LayoutUnit PaintLayerScrollableArea::scrollHeight() const
 {
     return m_overflowRect.height();
 }
 
 int PaintLayerScrollableArea::pixelSnappedScrollWidth() const
 {
-    return snapSizeToPixel(scrollWidth(), box().clientLeft() + box().location().x());
+    return snapSizeToPixel(scrollWidth(), box().clientLeft());
 }
 
 int PaintLayerScrollableArea::pixelSnappedScrollHeight() const
 {
-    return snapSizeToPixel(scrollHeight(), box().clientTop() + box().location().y());
+    return snapSizeToPixel(scrollHeight(), box().clientTop());
 }
 
 void PaintLayerScrollableArea::updateScrollOrigin()
 {
     // This should do nothing prior to first layout; the if-clause will catch that.
     if (overflowRect().isEmpty())
         return;
     LayoutPoint scrollableOverflow = m_overflowRect.location() - LayoutSize(box().borderLeft(), box().borderTop());
     setScrollOrigin(flooredIntPoint(-scrollableOverflow) + box().originAdjustmentForScrollbars());
 }
@@ skipping 1148 matching lines @@
 
 void PaintLayerScrollableArea::DelayScrollPositionClampScope::clampScrollableAreas()
 {
     for (auto& scrollableArea : *s_needsClamp)
         scrollableArea->clampScrollPositionsAfterLayout();
     delete s_needsClamp;
     s_needsClamp = nullptr;
 }
 
 } // namespace blink