Ensure visual overflow from style recalc gets propagated

third_party/WebKit/Source/core/layout/LayoutBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc.
  *               All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 2048 matching lines @@
     return false;
 
   LayoutUnit old_client_after_edge = HasOverflowModel()
                                          ? overflow_->LayoutClientAfterEdge()
                                          : ClientLogicalBottom();
   ComputeOverflow(old_client_after_edge, true);
 
   if (HasOverflowClip())
     Layer()->GetScrollableArea()->UpdateAfterOverflowRecalc();
 
-  return !HasOverflowClip();
+  return true;

[Xianzhu, 2017/05/23 20:35:42]

To keep the optimization for child overflow change not affecting overflow of
ancestors, I think this should be changed to:
  return !HasOverflowClip() || self_needs_overflow_recalc;
(with
   bool self_needed_overflow_recalc = SelfNeedsOverflowRecalcStyleChange()
 inserted before line 2052).

[rhogan, 2017/05/23 21:32:17]

OK, done!

 }
 
 // Called when a positioned object moves but doesn't necessarily change size.
 // A simplified layout is attempted that just updates the object's position.
 // If the size does change, the object remains dirty.
 bool LayoutBlock::TryLayoutDoingPositionedMovementOnly() {
   LayoutUnit old_width = LogicalWidth();
   LogicalExtentComputedValues computed_values;
   LogicalExtentAfterUpdatingLogicalWidth(LogicalTop(), computed_values);
   // If we shrink to fit our width may have changed, so we still need full
@@ skipping 115 matching lines @@
 bool LayoutBlock::HasDefiniteLogicalHeight() const {
   return AvailableLogicalHeightForPercentageComputation() != LayoutUnit(-1);
 }
 
 bool LayoutBlock::NeedsPreferredWidthsRecalculation() const {
   return (HasRelativeLogicalHeight() && Style()->LogicalWidth().IsAuto()) ||
          LayoutBox::NeedsPreferredWidthsRecalculation();
 }
 
 }  // namespace blink