lib,url: correct URL's argument to pass idlharness

`url.idl` defines URL's constructor as:

```
constructor(USVString url, optional USVString base);
```

`idlharness.any.js` checks its length as `1`. So we should remove
constructor's second argument and use `arguments[1]` in constructor's
logic.

Refs: https://url.spec.whatwg.org/#idl-index

lib/internal/url.js

@@ -621,7 +621,7 @@ function isURLThis(self) {
 }
 
 class URL {
-  constructor(input, base) {
+  constructor(input, base = undefined) {
     // toUSVString is not needed.
     input = `${input}`;
     let base_context;

test/wpt/status/url.json

@@ -13,9 +13,6 @@
   "urlencoded-parser.any.js": {
     "fail": "missing Request and Response"
   },
-  "idlharness.any.js": {
-    "fail": "getter/setter names are wrong, etc."
-  },
   "urlsearchparams-constructor.any.js": {
     "fail": "FormData is not defined"
   },

test/wpt/test-url.js

@@ -5,4 +5,5 @@ const { WPTRunner } = require('../common/wpt');
 
 const runner = new WPTRunner('url');
 
+runner.setInitScript('global.Window = global.__proto__.constructor;');
 runner.runJsTests();