[javascriptcore-test262-automation] Changes from...

[javascriptcore-test262-automation] Changes from https://github.com/webkit/webkit.git at sha 54374edc2b on Mon Oct 15 2018 18:40:44 GMT+0000 (Coordinated Universal Time)

implementation-contributed/javascriptcore/stress/json-stringify-no-arguments.js

+function shouldBe(actual, expected) {
+    if (actual !== expected)
+        throw new Error('bad value: ' + actual);
+}
+
+shouldBe(JSON.stringify(), undefined);
+shouldBe(JSON.stringify(undefined), undefined);