Provide mathjax support for <mathphrase> elements

ws/Docbook/CustomLayer/webhelp/hdmextensions.xsl

@@ -20,7 +20,7 @@
     <script type="text/javascript" src="common/jquery-jcarousel/jcarousel.basic.js"></script>
     <script type="text/javascript" src="common/jquery-jcarousel/jcarousel.data-attributes.js"></script>
     
-    <xsl:if test="//m:math">
+    <xsl:if test="//m:math|//d:mathphrase">
       <script type="text/x-mathjax-config">MathJax.Hub.Config({tex2jax: {inlineMath: [['$','$'], ['\\(','\\)']]}});</script>
       <script src="mathjax/MathJax.js?config=TeX-AMS-MML_HTMLorMML">
         <xsl:comment>Self closing tags disallowed!</xsl:comment>