Bug 1616681 [wpt PR 21886] - Fix typo in error message: promise_reject(s)_js, a=testonly

Automatic update from web-platform-tests
Fix typo in error message: promise_reject(s)_js (#21886)

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wpt-commits: de9fa20a3f15ccd89732a49077554da19d7ca40c
wpt-pr: 21886

testing/web-platform/tests/resources/testharness.js

@@ -641,7 +641,7 @@ policies and contribution forms [3].
     function promise_rejects_js(test, constructor, promise, description) {
         return promise.then(test.unreached_func("Should have rejected: " + description)).catch(function(e) {
             assert_throws_js_impl(constructor, function() { throw e },
-                                  description, "promise_reject_js");
+                                  description, "promise_rejects_js");
         });
     }