InitialColumnHeightFinder needs to take all expected rows into account.

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

 /*
  * Copyright (C) 2012 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 146 matching lines @@
     ASSERT(offsetInFlowThread.mightBeSaturated());
     remainingLogicalHeight = pageLogicalHeight;
   }
   return remainingLogicalHeight;
 }
 
 bool LayoutMultiColumnSet::isPageLogicalHeightKnown() const {
   return firstFragmentainerGroup().logicalHeight();
 }
 
+bool LayoutMultiColumnSet::newFragmentainerGroupsAllowed() const {
+  if (!isPageLogicalHeightKnown()) {
+    // If we have no clue about the height of the multicol container, bail. This
+    // situation occurs initially when an auto-height multicol container is
+    // nested inside another auto-height multicol container. We need at least an
+    // estimated height of the outer multicol container before we can check what
+    // an inner fragmentainer group has room for.
+    // Its height is indefinite for now.
+    return false;
+  }
+  if (isInitialHeightCalculated()) {
+    // We only insert additional fragmentainer groups in the initial layout
+    // pass. We only want to balance columns in the last fragmentainer group (if
+    // we need to balance at all), so we want that last fragmentainer group to
+    // be the same one in all layout passes that follow.
+    return false;
+  }
+  return true;
+}
+
 LayoutUnit LayoutMultiColumnSet::nextLogicalTopForUnbreakableContent(
     LayoutUnit flowThreadOffset,
     LayoutUnit contentLogicalHeight) const {
   ASSERT(flowThreadOffset.mightBeSaturated() ||
          pageLogicalTopForOffset(flowThreadOffset) == flowThreadOffset);
   FragmentationContext* enclosingFragmentationContext =
       multiColumnFlowThread()->enclosingFragmentationContext();
   if (!enclosingFragmentationContext) {
     // If there's no enclosing fragmentation context, there'll ever be only one
     // row, and all columns there will have the same height.
@@ skipping 429 matching lines @@
   // Now add in column rule bounds, if present.
   Vector<LayoutRect> columnRuleBounds;
   if (computeColumnRuleBounds(LayoutPoint(), columnRuleBounds)) {
     for (auto& bound : columnRuleBounds)
       blockFlowBounds.unite(bound);
   }
   return blockFlowBounds;
 }
 
 }  // namespace blink