[LayoutNG] Mark as fragmentainer when column-balancing.

When performing column layout, we need to tell the builder that it's to
generate a column box, as this determines the behavior when finishing
fragmentation; see IsFragmentainerBoxType() check in
FinalizeForFragmentation() in NGBlockLayoutAlgorithm). The other
entry points to column layout already take care of this, but it was
missing for the initial column balancing pass.

Bug: 829028
Change-Id: I60914b7adead19e4efa441d05733d4bd819dafd6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2440527
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812693}

third_party/blink/renderer/core/layout/ng/ng_column_layout_algorithm.cc

@@ -923,6 +923,7 @@ LayoutUnit NGColumnLayoutAlgorithm::CalculateBalancedColumnBlockSize(
   do {
     NGBlockLayoutAlgorithm balancing_algorithm(
         {Node(), fragment_geometry, space, break_token.get()});
+    balancing_algorithm.SetBoxType(NGPhysicalFragment::kColumnBox);
     scoped_refptr<const NGLayoutResult> result = balancing_algorithm.Layout();
 
     // This algorithm should never abort.

third_party/blink/web_tests/TestExpectations

@@ -1114,7 +1114,6 @@ crbug.com/1079031 virtual/layout_ng_block_frag/fast/multicol/out-of-flow/abspos-
 crbug.com/1079031 virtual/layout_ng_block_frag/fast/multicol/out-of-flow/abspos-auto-position-on-line.html [ Failure ]
 crbug.com/1079031 virtual/layout_ng_block_frag/fast/multicol/out-of-flow/abspos-auto-position-on-line-rtl.html [ Failure ]
 crbug.com/1079031 virtual/layout_ng_block_frag/fast/multicol/out-of-flow/nested-multicol.html [ Failure ]
-crbug.com/1066616 virtual/layout_ng_block_frag/fast/multicol/overflow-content.html [ Failure ]
 crbug.com/1079031 virtual/layout_ng_block_frag/fast/multicol/positioned-outside-of-columns.html [ Crash Failure ]
 crbug.com/1079031 virtual/layout_ng_block_frag/fast/multicol/positioned-split.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/shadow-breaking.html [ Failure ]