The column balancer should ignore things outside the bounds of the row.

third_party/WebKit/Source/core/dom/ContainerNode.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2013 Apple Inc. 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 841 matching lines @@
         return true;
     }
     return false;
 }
 
 static inline LayoutObject* endOfContinuations(LayoutObject* layoutObject)
 {
     LayoutObject* prev = nullptr;
     LayoutObject* cur = layoutObject;
 
-    if (!cur->isLayoutInline() && !cur->isLayoutBlock())
+    if (!cur->isLayoutInline() && !cur->isLayoutBlockFlow())
         return nullptr;
 
     while (cur) {
         prev = cur;
         if (cur->isLayoutInline())
             cur = toLayoutInline(cur)->continuation();
         else
-            cur = toLayoutBlock(cur)->continuation();
+            cur = toLayoutBlockFlow(cur)->continuation();
     }
 
     return prev;
 }
 
 bool ContainerNode::getLowerRightCorner(FloatPoint& point) const
 {
     if (!layoutObject())
         return false;
 
@@ skipping 503 matching lines @@
         return true;
 
     if (node->isElementNode() && toElement(node)->shadow())
         return true;
 
     return false;
 }
 #endif
 
 } // namespace blink