Removed unneeded reference to inv_def.

--- a/src/HOL/ex/LocaleTest2.thy	Mon Oct 19 16:45:00 2009 +0200
+++ b/src/HOL/ex/LocaleTest2.thy	Mon Oct 19 16:45:52 2009 +0200
@@ -897,7 +897,7 @@
 apply simp
 done
   show "Dmonoid.inv (op o) id f = inv (f :: unit => unit)"
-apply (unfold Dmonoid.inv_def [OF Dmonoid] inv_def)
+apply (unfold Dmonoid.inv_def [OF Dmonoid])
 apply (insert unit_id)
 apply simp
 apply (rule the_equality)