Correctly account for nested multicol top border / padding.

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

 // Copyright 2015 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 "core/layout/MultiColumnFragmentainerGroup.h"
 
 #include "core/layout/ColumnBalancer.h"
 #include "core/layout/FragmentationContext.h"
 #include "core/layout/LayoutMultiColumnSet.h"
 
@@ skipping 17 matching lines @@
 LayoutSize MultiColumnFragmentainerGroup::offsetFromColumnSet() const
 {
     LayoutSize offset(LayoutUnit(), logicalTop());
     if (!m_columnSet.flowThread()->isHorizontalWritingMode())
         return offset.transposedSize();
     return offset;
 }
 
 LayoutUnit MultiColumnFragmentainerGroup::blockOffsetInEnclosingFragmentationContext() const
 {
-    return logicalTop() + m_columnSet.logicalTop() + m_columnSet.multiColumnFlowThread()->blockOffsetInEnclosingFragmentationContext();
+    return logicalTop() + m_columnSet.logicalTopFromMulticolContentEdge() + m_columnSet.multiColumnFlowThread()->blockOffsetInEnclosingFragmentationContext();
 }
 
 void MultiColumnFragmentainerGroup::resetColumnHeight()
 {
     m_maxColumnHeight = calculateMaxColumnHeight();
 
     LayoutMultiColumnFlowThread* flowThread = m_columnSet.multiColumnFlowThread();
     if (m_columnSet.heightIsAuto()) {
         FragmentationContext* enclosingFragmentationContext = flowThread->enclosingFragmentationContext();
         if (enclosingFragmentationContext && enclosingFragmentationContext->isFragmentainerLogicalHeightKnown()) {
@@ skipping 483 matching lines @@
     append(MultiColumnFragmentainerGroup(m_columnSet));
     return last();
 }
 
 void MultiColumnFragmentainerGroupList::deleteExtraGroups()
 {
     shrink(1);
 }
 
 } // namespace blink