[css-text-3] Make boundary behavior of word-break/line-break/overflow-wrap undefined. w3c#3897

Author: fantasai

css-text-3/Overview.bs

@@ -2344,8 +2344,12 @@ Line Breaking Details</h3>
     <li>For <a>soft wrap opportunities</a> created by characters that disappear at the line break (e.g. U+0020 SPACE),
       properties on the box directly containing that character control the line breaking at that opportunity.
       For <a>soft wrap opportunities</a> defined by the boundary between two characters,
-      the properties on nearest common ancestor of the two characters controls breaking.
+      the 'white-space' property on the nearest common ancestor of the two characters controls breaking;
       <!-- http://lists.w3.org/Archives/Public/www-style/2008Dec/0043.html -->
+      which elements’ 'line-break', 'word-break', and 'overflow-wrap' properties
+      control the determination of [=soft wrap opportunities=]
+      at such boundaries
+      is undefined in Level 3.
 
       <wpt>
         line-breaking/line-breaking-009.html