[css-text-3] Clarify Arabic joining behavior at soft wraps. https://lists.w3.org/Archives/Public/www-style/2016Mar/0103.html https://lists.w3.org/Archives/Public/www-style/2016Mar/0160.html

Author: fantasai

css-text-3/Overview.bs

@@ -1232,12 +1232,13 @@ Shaping Across Intra-word Breaks</h3>
   ''overflow-wrap: break-word'',
   or when <a>hyphenating</a>)
   the characters must still be shaped
-  as if the word were not broken.
+  (its joining forms chosen)
+  as if the word were still whole.
 
   <div class="example">
     For example, if the word “نوشتن” is broken between the “ش” and “ت”,
-    the “ش” still takes its initial form (“ﺷ”), and the “ت” its medial form (“ﺘ”),
-    as in “ﻧﻮﺷﺘﻦ”.
+    the “ش” still takes its initial form (“ﺷ”), and the “ت” its medial form (“ﺘ”)--
+    forming as in “ﻧﻮﺷ | ﺘﻦ”, not as in “نوش | تن”.
   </div>
 
 <h2 id="justification">