Don't restore in LayoutBlock::layout if clamping is delayed.

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 738 matching lines @@
     // If a vertical scrollbar was removed, the min/max scroll positions may have changed,
     // so the scroll positions needs to be clamped.  If the scroll position did not change,
     // but the scroll origin *did* change, we still need to notify the scrollbars to
     // update their dimensions.
 
     if (DelayScrollPositionClampScope::clampingIsDelayed()) {
         DelayScrollPositionClampScope::setNeedsClamp(this);
         return;
     }
 
+    // Restore before clamping because clamping clears the scroll anchor.
+    if (shouldPerformScrollAnchoring())
+        m_scrollAnchor.restore();
+
     DoublePoint clamped = clampScrollPosition(scrollPositionDouble());
-    // Restore before clamping because clamping clears the scroll anchor.
-    if (clamped != scrollPositionDouble() && shouldPerformScrollAnchoring()) {
-        m_scrollAnchor.restore();
-        clamped = clampScrollPosition(scrollPositionDouble());
-    }
     if (clamped != scrollPositionDouble() || scrollOriginChanged())
         ScrollableArea::setScrollPosition(clamped, ProgrammaticScroll);
 
     setNeedsScrollPositionClamp(false);
     resetScrollOriginChanged();
     m_scrollbarManager.destroyDetachedScrollbars();
 }
 
 bool PaintLayerScrollableArea::shouldPerformScrollAnchoring() const
 {
@@ skipping 997 matching lines @@
 
 void PaintLayerScrollableArea::DelayScrollPositionClampScope::clampScrollableAreas()
 {
     for (auto& scrollableArea : *s_needsClamp)
         scrollableArea->clampScrollPositionsAfterLayout();
     delete s_needsClamp;
     s_needsClamp = nullptr;
 }
 
 } // namespace blink