Invalid URL parsing

While this doesn't fail on Lightpanda:
```js
let a = new URL("://foo.bar/path?query#fragment");
// a.protocol => ":"
```

It fails on Chrome:
```js
let a = new URL("://foo.bar/path?query#fragment");
```
```
VM217:1 Uncaught TypeError: Failed to construct 'URL': Invalid URL
    at <anonymous>:1:5
```