Merge remote-tracking branch 'origin/MAGETWO-58367' into Kanban-2-PR-2.2

Author: eug123

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

@@ -140,7 +140,7 @@
 
     <xs:simpleType name="elementNameType">
         <xs:restriction base="xs:string">
-            <xs:pattern value="[a-zA-Z][a-zA-Z\d\-_\.]*"/>
+            <xs:pattern value="[a-zA-Z0-9][a-zA-Z\d\-_\.]*"/>
         </xs:restriction>
     </xs:simpleType>