column-rule should fill the entire height of columns even if there weren't enough contents because "column-fill: balance" distributed the contents. See http://www.w3.org/TR/css3-multicol/#column-gaps-and-rules This bug was found by the newly imported test: LayoutTests/imported/w3c/css/css-multicol-1/multicol-rule-004.xht
<rdar://problem/22583152>
Safari Technology Preview 179 still failing this test as only browser. Added 'WPTImpact' because it is on WPT and also only Safari is failing, hence I am adding 'BrowserCompat' as well.