This fix should be as simple as adding 2 lines below to NGBlockLayoutAlgorithm::FinishChildLayout
if (child->Style().Clear() != EClear::kNone)
content_size_ = logical_offset.block_offset + fragment.BlockSize();
affected layout tests
virtual/layout_ng/external/wpt/css/CSS2/floats-clear/floats-029.xht
virtual/layout_ng/external/wpt/css/CSS2/floats-clear/floats-144.xht
virtual/layout_ng/external/wpt/css/CSS2/floats-clear/margin-collapse-018.xht
virtual/layout_ng/external/wpt/css/CSS2/floats-clear/margin-collapse-027.xht
Comment 1 by glebl@chromium.org
, May 25 2017