Revert accidentally checked in change in r281315.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@281316 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaLookup.cpp

@@ -1339,7 +1339,7 @@ Module *Sema::getOwningModule(Decl *Entity) {
     // instance, maybe this is a lazily-declared special member of an imported
     // class).
     auto *Parent = cast<NamedDecl>(Entity->getDeclContext());
-    assert(!Parent->isHidden() && "unexpectedly hidden decl");
+    assert(Parent->isHidden() && "unexpectedly hidden decl");
     return getOwningModule(Parent);
   }