Simplify using available standard DOM method.

ws/Docbook/CustomLayer/Common/common.xsl

@@ -14,23 +14,21 @@
   
   <xsl:param name="toggleDisplayScript">
     <script xmlns="http://www.w3.org/1999/xhtml" type="text/javascript"> <!-- goiks extension head start -->
-      function toggleDisplay(inputEl) {
-      divElem = nextSibling(inputEl);
-      if (divElem.style.visibility == 'hidden') {
-      divElem.style.visibility = 'visible';
-      inputEl.setAttribute('value','-');
-      } else {
-      divElem.style.visibility = 'hidden';
-      inputEl.setAttribute('value','+');
-      }
-      }
-      function nextSibling(n) {
-      x=n.nextSibling;
-      while (x.nodeType!=1) {
-      x=x.nextSibling;
-      }
-      return x;
-      }
+    "use strict";
+    function toggleDisplay(inputElement) {
+        var divElement = inputElement.nextElementSibling;
+
+        switch(divElement.style.visibility) {
+            case 'hidden':
+                divElement.style.visibility = 'visible';
+                inputElement.setAttribute('value', '-');
+                break;
+            default:
+                divElement.style.visibility = 'hidden';
+                inputElement.setAttribute('value', '+');
+                break;
+        }
+    }
     </script>
   </xsl:param>
   
@@ -87,4 +85,4 @@
   </xsl:template>
   
   
-</xsl:stylesheet>
\ No newline at end of file
+</xsl:stylesheet>