Support enclosing fragmentainer breaks inside spanners.

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/layout/LayoutMultiColumnSpannerPlaceholder.h"
 
 namespace blink {
 
 static void copyMarginProperties(ComputedStyle& placeholderStyle, const ComputedStyle& spannerStyle)
@@ skipping 73 matching lines @@
 
 LayoutUnit LayoutMultiColumnSpannerPlaceholder::maxPreferredLogicalWidth() const
 {
     return m_layoutObjectInFlowThread->maxPreferredLogicalWidth();
 }
 
 void LayoutMultiColumnSpannerPlaceholder::layout()
 {
     ASSERT(needsLayout());
 
+    // The placeholder, like any other block level object, has its logical top calculated and set
+    // before layout. Copy this to the actual column-span:all object before laying it out, so that
+    // it gets paginated correctly, in case we have an enclosing fragmentation context.
+    m_layoutObjectInFlowThread->setLogicalTop(logicalTop());
+
     // Lay out the actual column-span:all element.
     m_layoutObjectInFlowThread->layoutIfNeeded();
 
     // The spanner has now been laid out, so its height is known. Time to update the placeholder's
     // height as well, so that we take up the correct amount of space in the multicol container.
     updateLogicalHeight();
 
     // Take the overflow from the spanner, so that it gets
     // propagated to the multicol container and beyond.
     m_overflow.clear();
@@ skipping 23 matching lines @@
     if (!m_layoutObjectInFlowThread->hasSelfPaintingLayer())
         m_layoutObjectInFlowThread->paint(paintInfo, paintOffset);
 }
 
 bool LayoutMultiColumnSpannerPlaceholder::nodeAtPoint(HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction action)
 {
     return !m_layoutObjectInFlowThread->hasSelfPaintingLayer() && m_layoutObjectInFlowThread->nodeAtPoint(result, locationInContainer, accumulatedOffset, action);
 }
 
 }