Allow more htmlClasses

Author: barryvdh

lib/internal/Magento/Framework/View/Layout/etc/elements.xsd

@@ -119,7 +119,7 @@
 
     <xs:simpleType name="htmlClassType">
         <xs:restriction base="xs:string">
-            <xs:pattern value="[a-zA-Z][a-zA-Z\d\-_:]*(\s[a-zA-Z][a-zA-Z\d\-_:]*)*"/>
+            <xs:pattern value="[a-zA-Z\-][a-zA-Z\d\-_/:.\[\]]*(\s[a-zA-Z][a-zA-Z\d\-_/:.\[\]]*)*"/>
         </xs:restriction>
     </xs:simpleType>