Array::push and Array.from unbox native types

[jcubic]

This is really problematic:

(let ((x (vector)))
  (x.push #\x)
  x)
;; ==> #("x")

This prevents adding:

LString.prototype[Symbol.iterator] = function*() {
    const chars = Array.from(this.__string__);
    for (const char of chars) {
        yield LCharacter(char);
    }
};

because they got unboxed.

Another issue is that:

(Array.from "hello")

doesn't trigger LString iterator, because string is unboxed.

[jcubic]

Possible solutions:

• Adding a marker to native types to prevent them unboxed for a single native method.
• Add wrappers for common Array methods
• Make LCharacter unboxable, it will break when using char with JavaScript libraries but it's good because they will be not compatible.

[jcubic]

this code still doesn't work:

(Array.from "hello")
;; ==> #("h" "e" "l" "l" "o")

Because the string is unboxed before getting the iterator:

(let ((i (. "hello" Symbol.iterator)))
  (Array.from (i)))
;; ==> #(#\h #\e #\l #\l #\o)

Strings have to be unboxed.