Fix reference to global's document

Author: antosart

index.bs

@@ -1123,7 +1123,7 @@ spec:SRI; urlPrefix: https://w3c.github.io/webappsec-subresource-integrity
   1.  Let |global| be the |request|'s [=request/client=]'s [=/global object=].
   1.  If |global| is not a {{Window}}, return.
   1.  Let |stripped document URL| to be the result of executing [[#strip-url-for-use-in-reports]]
-      on |global|'s [=document=]'s [=Document/URL=].
+      on |global|'s {{Window/document}}'s [=Document/URL=].
   1.  If |policy|'s [=directive set=] does not contain a [=directive=] named "report-to", return.
   1.  Let |report-to directive| be a [=directive=] named "report-to" from |policy|'s [=directive
       set=].