Std.parseInt returns an UInt on JS target

```haxe
class Main {
static function main() {
trace( Std.parseInt("0xaabbccdd") ); // 2864434397
trace( 0xaabbccdd ); // -1430532899
trace( Std.parseInt("0xaabbccdd") == 0xaabbccdd ); // false
}
}
```

Reproduce the provided Main example on the JS target, focusing on Std.parseInt and the hexadecimal literal comparison. Trace the relevant compiler or runtime entry point for Std.parseInt; done means the parsed hexadecimal value has the intended signedness and the demonstrated comparison behaves consistently.

Written by the indexing model from the issue text.