LayoutRect RenderBox::layoutOverflowRectForPropagation(const WritingMode parentWritingMode) const { ... // As per https://drafts.csswg.org/css-overflow-3/#scrollable, both flex and grid items margins' should contribute to the scrollable overflow area. if (shouldMarginInlineEndContributeToScrollableOverflow(*this)) { auto marginEnd = std::max(0_lu, this->marginEnd(parentWritingMode)); parentWritingMode.isHorizontal() ? rect.setWidth(rect.width() + marginEnd) : rect.setHeight(rect.height() + marginEnd); } This code is redundant with the contentArea handling added in https://bugs.webkit.org/show_bug.cgi?id=286472 and probably should be removed.