Mark final types as exact (#88163)

Co-authored-by: NAndy Ayers <andya@microsoft.com>

src/coreclr/jit/gentree.cpp

@@ -18261,6 +18261,10 @@ CORINFO_CLASS_HANDLE Compiler::gtGetClassHandle(GenTree* tree, bool* pIsExact, b
             *pIsExact = true;
             objClass  = exactClass;
         }
+        else
+        {
+            *pIsExact = impIsClassExact(objClass);
+        }
     }
 
     return objClass;