Clear box from percentage descendants when it is split off from the ancestor

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. 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 4355 matching lines @@
         toLayoutTable(box)->forceSectionsRecalc();
     } else if (box->isTableSection()) {
         toLayoutTableSection(box)->setNeedsCellRecalc();
     }
 
     box->setNeedsLayoutAndPrefWidthsRecalcAndFullPaintInvalidation(LayoutInvalidationReason::AnonymousBlockChange);
 }
 
 LayoutObject* LayoutBox::splitAnonymousBoxesAroundChild(LayoutObject* beforeChild)
 {
-    bool didSplitParentAnonymousBoxes = false;
+    LayoutBox* boxAtTopOfNewBranch = nullptr;
 
     while (beforeChild->parent() != this) {
         LayoutBox* boxToSplit = toLayoutBox(beforeChild->parent());
         if (boxToSplit->slowFirstChild() != beforeChild && boxToSplit->isAnonymous()) {
-            didSplitParentAnonymousBoxes = true;
 
             // We have to split the parent box into two boxes and move children
             // from |beforeChild| to end into the new post box.
             LayoutBox* postBox = boxToSplit->createAnonymousBoxWithSameTypeAs(this);
             postBox->setChildrenInline(boxToSplit->childrenInline());
             LayoutBox* parentBox = toLayoutBox(boxToSplit->parent());
             // We need to invalidate the |parentBox| before inserting the new node
             // so that the table paint invalidation logic knows the structure is dirty.
             // See for example LayoutTableCell:clippedOverflowRectForPaintInvalidation.
             markBoxForRelayoutAfterSplit(parentBox);
             parentBox->virtualChildren()->insertChildNode(parentBox, postBox, boxToSplit->nextSibling());
             boxToSplit->moveChildrenTo(postBox, beforeChild, 0, true);
 
             markBoxForRelayoutAfterSplit(boxToSplit);
             markBoxForRelayoutAfterSplit(postBox);
+            boxAtTopOfNewBranch = postBox;
 
             beforeChild = postBox;
         } else {
             beforeChild = boxToSplit;
         }
     }
 
-    if (didSplitParentAnonymousBoxes)
+    // Splitting the box means the left side of the container chain will lose any percent height descendants
+    // below |boxAtTopOfNewBranch| on the right hand side.
+    if (boxAtTopOfNewBranch && LayoutBlock::hasPercentHeightContainerMap())
+        LayoutBlock::clearPercentHeightDescendantsFrom(boxAtTopOfNewBranch);
+
+    if (boxAtTopOfNewBranch)

[mstensho (USE GERRIT), 2016/01/25 19:37:07]

We could if for |boxAtTopOfNewBranch| only once.

if (boxAtTopOfNewBranch) {
    // bla bla
    if (LayoutBlock::hasPercentHeightContainerMap())
        LayoutBlock::clearPercentHeightDescendantsFrom(boxAtTopOfNewBranch);

    markBoxForRelayoutAfterSplit(this);
}

         markBoxForRelayoutAfterSplit(this);
 
     ASSERT(beforeChild->parent() == this);
     return beforeChild;
 }
 
 LayoutUnit LayoutBox::offsetFromLogicalTopOfFirstPage() const
 {
     LayoutState* layoutState = view()->layoutState();
     if (!layoutState || !layoutState->isPaginated())
@@ skipping 190 matching lines @@
 }
 
 void LayoutBox::clearPreviousPaintInvalidationRects()
 {
     LayoutBoxModelObject::clearPreviousPaintInvalidationRects();
     if (PaintLayerScrollableArea* scrollableArea = this->scrollableArea())
         scrollableArea->clearPreviousPaintInvalidationRects();
 }
 
 } // namespace blink