Distinguish between row (fragmentainer group) height and column (fragmentainer) height.

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

 // Copyright 2016 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/FragmentainerIterator.h"
 
 #include "core/layout/LayoutMultiColumnSet.h"
 
 namespace blink {
 
@@ skipping 53 matching lines @@
     if (AtEnd())
       return;
   }
 }
 
 LayoutSize FragmentainerIterator::PaginationOffset() const {
   DCHECK(!AtEnd());
   const MultiColumnFragmentainerGroup& group = CurrentGroup();
   LayoutUnit fragmentainer_logical_top_in_flow_thread =
       group.LogicalTopInFlowThread() +
-      current_fragmentainer_index_ * group.LogicalHeight();
+      current_fragmentainer_index_ * group.ColumnLogicalHeight();
   return group.FlowThreadTranslationAtOffset(
       fragmentainer_logical_top_in_flow_thread,
       LayoutBox::kAssociateWithLatterPage, CoordinateSpaceConversion::kVisual);
 }
 
 LayoutRect FragmentainerIterator::ClipRectInFlowThread(
     MultiColumnFragmentainerGroup::ClipRectAxesSelector axes_selector) const {
   DCHECK(!AtEnd());
   LayoutRect clip_rect = CurrentGroup().FlowThreadPortionOverflowRectAt(
       current_fragmentainer_index_, axes_selector);
@@ skipping 63 matching lines @@
     if (current_fragmentainer_index_ < first_fragmentainer_in_clip_rect)
       current_fragmentainer_index_ = first_fragmentainer_in_clip_rect;
     if (end_fragmentainer_index_ > last_fragmentainer_in_clip_rect)
       end_fragmentainer_index_ = last_fragmentainer_in_clip_rect;
   }
   DCHECK_GE(end_fragmentainer_index_, current_fragmentainer_index_);
   return true;
 }
 
 }  // namespace blink