Tie scroll anchoring adjustments to frame lifecycle instead of layout.

third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 955 matching lines @@
   if (!frame() || !frame()->host())
     return 0;
 
   if (!frame()->host()->settings().inertVisualViewport())
     return m_visualViewport->pageX();
 
   FrameView* view = frame()->view();
   if (!view)
     return 0;
 
-  document()->updateStyleAndLayoutIgnorePendingStylesheets();
+  document()->updateScrollPosition();
 
   double viewportX =
       view->layoutViewportScrollableArea()->scrollOffset().width();
   return adjustScrollForAbsoluteZoom(viewportX, frame()->pageZoomFactor());
 }
 
 double LocalDOMWindow::scrollY() const {
   if (!frame() || !frame()->host())
     return 0;
 
   if (!frame()->host()->settings().inertVisualViewport())
     return m_visualViewport->pageY();
 
   FrameView* view = frame()->view();
   if (!view)
     return 0;
 
-  document()->updateStyleAndLayoutIgnorePendingStylesheets();
+  document()->updateScrollPosition();
 
   double viewportY =
       view->layoutViewportScrollableArea()->scrollOffset().height();
   return adjustScrollForAbsoluteZoom(viewportY, frame()->pageZoomFactor());
 }
 
 DOMVisualViewport* LocalDOMWindow::visualViewport() {
   if (!frame())
     return nullptr;
 
@@ skipping 550 matching lines @@
 
 LocalFrame* LocalDOMWindow::frame() const {
   // If the LocalDOMWindow still has a frame reference, that frame must point
   // back to this LocalDOMWindow: otherwise, it's easy to get into a situation
   // where script execution leaks between different LocalDOMWindows.
   SECURITY_DCHECK(!m_frame || m_frame->domWindow() == this);
   return m_frame;
 }
 
 }  // namespace blink