[css-text-3] plaintext line boxes without a strong direction use directionality of previous line. #4405

Author: fantasai

css-text-3/Overview.bs

@@ -5695,7 +5695,8 @@ Bidirectionality and Line Boxes</h3>
     that is, the <a>bidi paragraph</a> for which the line box holds content.
     An empty line box
     (i.e. one that contains no atomic inlines or
-     characters other than the line-breaking character, if any),
+     characters other than the line-breaking character, if any)
+    or one that contains only weak or neutral characters,
     takes its <a>inline base direction</a> from the preceding line box (if any), or,
     if this is the first line box in the containing block,
     then from the 'direction' property of the containing block.