[CSS22] Updated the changed text in 9.9.1 for 'z-index: auto'.

Author: bert-github

css2/changes.src

@@ -925,13 +925,12 @@ term
       <dt><strong>auto</strong> <dd>The stack level of the generated
        box in the current stacking context is 0. <del>The box does not
        establish a new stacking context unless it is the root
-       element.</del> <ins>[TBD] <!-- If the box has 'position: fixed'
-       or if it is the root, it establishes a new stacking
-       content. --></ins>
+       element.</del> <ins>If the box has 'position: fixed' or if it
+       is the root, it also establishes a new stacking context.</ins>
      </dl>
     </blockquote>
 
-    <!-- Status: not edited, waiting for concrete text -->
+    <!-- Status: edited, but WG still needs to validate the text -->
     <!-- https://lists.w3.org/Archives/Public/www-style/2015Jul/0032.html -->