Add test case from JS

test/xref2/js_stack_overflow.t/a.mli

@@ -0,0 +1,4 @@
+open! Import
+include S
+module Thing : sig end
+

test/xref2/js_stack_overflow.t/import.mli

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+module type S0 = sig
+  module Thing : sig
+    module Config : sig end
+  end
+end
+
+module type S = sig
+  include S0
+
+  module Thing : sig
+    module Config = Thing.Config
+  end
+end

test/xref2/js_stack_overflow.t/run.t

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+A bug report from JS. This code was causing a loop / stack overflow. Success is
+simply finishing!
+
+  $ ocamlc -c import.mli -bin-annot
+  $ ocamlc -c a.mli -bin-annot
+
+  $ odoc compile import.cmti -I .
+  $ odoc compile a.cmti -I .
+
+  $ odoc link import.odoc -I .
+  $ odoc link a.odoc -I .
+
+  $ odoc_print --short a.odocl --show-expansions --show-include-expansions
+  open [  ]
+  include Import.S
+    (sig :
+      include Import.S0
+        (sig :
+          module {Thing}1/shadowed/(74ad8508d0ec544850c6ab547111f52a) : 
+            sig module Config : sig  end end
+         end)
+      module {Thing}1/shadowed/(1a743df82e4f1cc649e915544d526dea) : 
+        sig
+          module Config =
+            {Thing}1/shadowed/(74ad8508d0ec544850c6ab547111f52a).Config
+            (sig :  end)
+        end
+     end)
+  module Thing : sig  end
+
+