`xref-binding->definition-tag': fix two-argument-list mode

Closes PR 11847

original commit: 00ca86ffc6641892828a0444babd00357a03bb82

collects/scribble/xref.rkt

@@ -106,7 +106,7 @@
          (let loop ([src (car id/binding)])
            (cond
             [(module-path-index? src)
-             (search src)]
+             (search (list src (cadr id/binding)))]
             [(module-path? src)
              (loop (module-path-index-join src #f))]
             [else

collects/tests/scribble/xref.rkt

@@ -0,0 +1,21 @@
+#lang racket/base
+(require scribble/xref
+         racket/fasl
+         setup/dirs)
+
+(define xref (load-xref (list 
+                         (lambda ()
+                           (cadr
+                            (call-with-input-file*
+                             (build-path (find-doc-dir)
+                                         "reference"
+                                         "out.sxref")
+                             fasl->s-exp))))))
+
+(unless (equal? '(form ((lib "racket/contract.rkt") ->))
+                (xref-binding->definition-tag 
+                 xref 
+                 (list '(lib "contract.rkt" "racket") '->)
+                 #f))
+  (error "failed"))
+