[JS] window.onerror signature

Hej,

Sorry for reporting much issues these last days but as you can notice I play with errors/exceptions ans so on... ^^'

Sometimes I make PR to adjust some targets things that are wrong or that are missing without annoying you with that, but here, I wanted your advice about the signature of `js.html.Window` `onerror`function which is in Haxe like this : `var onerror : haxe.extern.EitherType -> String -> Int -> Int -> Dynamic -> Dynamic;` (https://github.com/HaxeFoundation/haxe/blob/development/std/js/html/Window.hx#L335) while in the "offical" documentation it is supposed to be like that : `message : String, source : String, lineno : Int, colno : Int, error : js.Error -> Bool` (https://developer.mozilla.org/en-US/docs/Web/API/Window/error_event)

Is there a reason for something like that please ?

EDIT : the signature should be like this class' variables : `js.html.ErrorEvent` (https://github.com/HaxeFoundation/haxe/blob/development/std/js/html/ErrorEvent.hx)

Thanks for reading me