fix(testharness): copy-pasta in assert_throws_dom (web-platform-tests…

…#46566)

This regressed in web-platform-tests#46487

resources/testharness.js

@@ -2174,7 +2174,7 @@
             func = funcOrConstructor;
             description = descriptionOrFunc;
             assert(maybeDescription === undefined,
-                   "Too many args passed to no-constructor version of promise_rejects_dom, or accidentally explicitly passed undefined");
+                   "Too many args passed to no-constructor version of assert_throws_dom, or accidentally explicitly passed undefined");
         }
         assert_throws_dom_impl(type, func, description, "assert_throws_dom", constructor)
     }