Update ReferenceBlock Class

Including the "class" attribute to the typeReferenceBlock definition allows you to update a block class when overriding or updating a layout.xml file without the need to remove the original block and re-add it with the same name but different class.

Author: leandrommedeiros

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

@@ -313,6 +313,7 @@
         </xs:choice>
         <xs:attribute type="elementNameType" name="name" use="required"/>
         <xs:attribute type="xs:string" name="template" use="optional"/>
+        <xs:attribute type="xs:string" name="class" use="optional"/>
         <xs:attribute type="xs:boolean" name="display" default="true" use="optional"/>
         <xs:attribute type="xs:boolean" name="remove" use="optional"/>
     </xs:complexType>