Invalidate CustomScrollbars on having window-inactive selector.

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 322 matching lines @@
     }
     if (didStyleChange) {
         updateScrollbarGeometry();
         updateScrollCorner();
         positionScrollbarLayers();
     }
 }
 
 void FrameView::invalidateAllCustomScrollbarsOnActiveChanged()
 {
+    bool usesWindowInactiveSelector = m_frame->document()->styleEngine()->usesWindowInactiveSelector();
+
     const ChildrenWidgetSet* viewChildren = children();
     for (const RefPtrWillBeMember<Widget>& child : *viewChildren) {
         Widget* widget = child.get();
         if (widget->isFrameView())
             toFrameView(widget)->invalidateAllCustomScrollbarsOnActiveChanged();
-        else if (widget->isScrollbar() && toScrollbar(widget)->isCustomScrollbar())
+        else if (usesWindowInactiveSelector && widget->isScrollbar() && toScrollbar(widget)->isCustomScrollbar())
             toScrollbar(widget)->styleChanged();
     }
-    recalculateCustomScrollbarStyle();
+    if (usesWindowInactiveSelector)
+        recalculateCustomScrollbarStyle();
 }
 
 void FrameView::recalculateScrollbarOverlayStyle()
 {
     ScrollbarOverlayStyle oldOverlayStyle = scrollbarOverlayStyle();
     ScrollbarOverlayStyle overlayStyle = ScrollbarOverlayStyleDefault;
 
     Color backgroundColor = documentBackgroundColor();
     // Reduce the background color from RGB to a lightness value
     // and determine which scrollbar style to use based on a lightness
@@ skipping 3643 matching lines @@
         return;
 
     ScrollableArea::setScrollOrigin(origin);
 
     // Update if the scroll origin changes, since our position will be different if the content size did not change.
     if (updatePositionAtAll && updatePositionSynchronously)
         updateScrollbars(scrollOffsetDouble());
 }
 
 } // namespace blink