[New Multicolumn] Spanners are not part of the nearest ancestor flow thread.

Source/core/paint/DeprecatedPaintLayer.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@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 504 matching lines @@
     // genuinely know if it is going to have to split itself up when painting only its contents (and not any other descendant
     // layers). We track an enclosingPaginationLayer instead of using a simple bit, since we want to be able to get back
     // to that layer easily.
     if (usesRegionBasedColumns && layoutObject()->isLayoutFlowThread()) {
         m_enclosingPaginationLayer = this;
         return;
     }
 
     if (m_stackingNode->isNormalFlowOnly()) {
         if (usesRegionBasedColumns) {
-            // Content inside a transform is not considered to be paginated, since we simply
-            // paint the transform multiple times in each column, so we don't have to use
-            // fragments for the transformed content.
-            m_enclosingPaginationLayer = parent()->enclosingPaginationLayer();
-            if (m_enclosingPaginationLayer && m_enclosingPaginationLayer->hasTransformRelatedProperty())
-                m_enclosingPaginationLayer = 0;
+            // We cannot take the fast path for spanners, as they do not have their nearest ancestor
+            // pagination layer (flow thread) in their containing block chain.
+            if (!layoutObject()->isColumnSpanAll()) {
+                // Content inside a transform is not considered to be paginated, since we simply
+                // paint the transform multiple times in each column, so we don't have to use
+                // fragments for the transformed content.
+                m_enclosingPaginationLayer = parent()->enclosingPaginationLayer();
+                if (m_enclosingPaginationLayer && m_enclosingPaginationLayer->hasTransformRelatedProperty())
+                    m_enclosingPaginationLayer = 0;
+                return;
+            }
         } else {
             m_isPaginated = parent()->layoutObject()->hasColumns();
+            return;
         }
-        return;
     }
 
     // For the new columns code, we want to walk up our containing block chain looking for an enclosing layer. Once
     // we find one, then we just check its pagination status.
     if (usesRegionBasedColumns) {
         LayoutView* view = layoutObject()->view();
         LayoutBlock* containingBlock;
         for (containingBlock = layoutObject()->containingBlock();
             containingBlock && containingBlock != view;
             containingBlock = containingBlock->containingBlock()) {
@@ skipping 2420 matching lines @@
     }
 }
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject)
         return;
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif