`new` operator support in `js` library

[kateinoigakukun]

Discussed in #165

^{Originally posted by scally February 14, 2023}
How do you call new on Javascript objects? I haven't found a workaround yet that will let me do this. I can call the object constructor but it will then tell me that I need to call the new operator:

for example:

observer = JS.global.MutationObserver do
  puts 'here'
end

results in

TypeError: Constructor requires 'new' operator (JS::Error)
```</div>

[SatorSight]

Couldn't find proper Ruby solution, so had to use:
offset_canvas = JS.eval('return new OffscreenCanvas(1, 2)')
This at least properly returns usable object.

[kateinoigakukun]

Closed by #246