benchmark: add USVString conversion benchmark

PR-URL: #11436
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>

benchmark/url/usvstring.js

@@ -0,0 +1,28 @@
+'use strict';
+const common = require('../common.js');
+
+const inputs = {
+  valid: 'adsfadsfadsf',
+  validsurr: '\uda23\ude23\uda1f\udfaa\ud800\udfff\uda23\ude23\uda1f\udfaa' +
+             '\ud800\udfff',
+  someinvalid: 'asasfdfasd\uda23',
+  allinvalid: '\udc45\uda23 \udf00\udc00 \udfaa\uda12 \udc00\udfaa',
+  nonstring: { toString() { return 'asdf'; } }
+};
+const bench = common.createBenchmark(main, {
+  input: Object.keys(inputs),
+  n: [5e7]
+}, {
+  flags: ['--expose-internals']
+});
+
+function main(conf) {
+  const { toUSVString } = require('internal/url');
+  const str = inputs[conf.input];
+  const n = conf.n | 0;
+
+  bench.start();
+  for (var i = 0; i < n; i++)
+    toUSVString(str);
+  bench.end(n);
+}