test: add test for URLSearchParams inspection

The member methods of URLSearchParams should split across multiple
lines with `util.inspect` depending on an option `breakLength`.

PR-URL: nodejs#11428
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

test/parallel/test-whatwg-url-searchparams-inspect.js

@@ -13,6 +13,8 @@ assert.strictEqual(util.inspect(sp.keys()),
                    "URLSearchParamsIterator { 'a', 'b', 'b' }");
 assert.strictEqual(util.inspect(sp.values()),
                    "URLSearchParamsIterator { 'a', 'b', 'c' }");
+assert.strictEqual(util.inspect(sp.keys(), {breakLength: 1}),
+                   "URLSearchParamsIterator {\n  'a',\n  'b',\n  'b' }");
 
 const iterator = sp.entries();
 assert.strictEqual(util.inspect(iterator),