Breaks and labels interact incorrectly

[WardBrian]

This is essentially me duplicating bellard/quickjs#275 here, since it seems to still affect quickjs-ng:

./qjs-linux-x86_64 -e 'for (var i=0; i<4; i++)
label: {
  console.log(i);
  if (i === 1) {
    console.log("break");
    break;
  }
}'

prints

0
1
break
2
3

When the expected output does not print 2 or 3.

In particular, this seems to be an issue when using quickjs with code created the js_of_ocaml Ocaml->JS compiler, as this has moved to heavy use of labels and break statements for ocsigen/js_of_ocaml#1496

[bnoordhuis]

Hah, it's even worse - the while variant just hangs:

var i = 0; while (i < 3) label: {
  if (i > 0) break
  i++
}

Fix incoming!

[bnoordhuis]

For posterity: the fix also fixes bellard/quickjs#282

[saghul]

Ha, nice one!