[css-writing-modes] Fix validation issue caused by bikeshed

Author: kojiishi

css-writing-modes/Overview.html

@@ -129,11 +129,11 @@ <h2 class="no-num no-toc no-ref heading settled heading" id=contents><span class
 Compression Rules</a><ul class=toc><li><a href=#text-combine-fullwidth><span class=secno>9.1.2.1</span>
 Full-width Characters</a></ul></ul></ul><li><a href=#changes><span class=secno></span>Changes</a><ul class=toc><li><a href=#changes-201211><span class=secno></span>
   Changes since the <span>November
-  2012 CSS Writing Modes Module Level 3 <spanbbr title="Working Draft">WD</spanbbr></span></a><li><a href=#changes-201205><span class=secno></span>
+  2012 CSS Writing Modes Module Level 3 <abbr title="Working Draft">WD</abbr></span></a><li><a href=#changes-201205><span class=secno></span>
   Changes since the <span>May
-  2012 CSS Writing Modes Module Level 3 <spanbbr title="Working Draft">WD</spanbbr></span></a><li><a href=#changes-201109><span class=secno></span>
+  2012 CSS Writing Modes Module Level 3 <abbr title="Working Draft">WD</abbr></span></a><li><a href=#changes-201109><span class=secno></span>
   Changes since the <span>September
-  2011 CSS Writing Modes Module Level 3 <spanbbr title="Working Draft">WD</spanbbr></span></a></ul><li><a href=#acknowledgements><span class=secno></span>
+  2011 CSS Writing Modes Module Level 3 <abbr title="Working Draft">WD</abbr></span></a></ul><li><a href=#acknowledgements><span class=secno></span>
 Acknowledgements</a><li><a href=#character-properties><span class=secno></span>Appendix A.
 Characters and Properties</a><li><a href=#bidi-html><span class=secno></span>
 Appendix B: Bidi Rules for HTML 4</a><li><a href=#script-orientations><span class=secno></span>Appendix C: