Fix missing attribute name in returned tuple for event handler case

spec/index.bs

@@ -1106,7 +1106,7 @@ To <dfn abstract-op>Get Trusted Type data for attribute</dfn> given |element|, |
 
 1. Let |data| be null.
 1. If |attributeNs| is null, and |attribute| is the name of an [=event handler content attribute=], then:
-    1. Return ({{Element}}, null, {{TrustedScript}}, "Element " + |attribute|).
+    1. Return ({{Element}}, null, |attribute|, {{TrustedScript}}, "Element " + |attribute|).
 1. Find the row in the following table, where |element| is in the first column, |attributeNs| is in the second column,
     and |attribute| is in the third column.
     If a matching row is found, set |data| to that row.