Added an issue for text-transform:fullwidth for when the glyph is missing

Author: kojiishi

css3-text/Overview.src.html

@@ -3546,7 +3546,9 @@ <h3 id="text-transform"><span class="secno">10.1</span><a name="caps-prop"></a>
           If the character does not have corresponding fullwidth form,
           it is left as is.
           This value is typically used to typeset Latin characters and digits
-          like ideographic characters.</dd>
+          like ideographic characters.
+          <p class="issue">should try fallback if the glyph is missing.
+            should it also check fullwidth variants before falling back to next font?</p></dd>
       <dt><dfn title="text-transform:large-kana"><code>large-kana</code></dfn></dt>
         <dd>Converts all small Kana characters to normal Kana.
           This value is typically used for ruby annotation text,