Remove unknown named targets

[Exagone313]

When an unknown name is used as a target, link is opened in a new tab.

Currently, the extension only removes targets starting by _, but some sites use wrong values for target such as blank or new.

Valid names can be retrieved from window.frames array and its members' own frames property recursively.

PS: This would probably break a website adding links before frames are created/loaded.

I'd like to look into submitting a PR.

[Exagone313]

Example script for listing frame names recursively (incomplete, need also to check el.parent when != el)

function print_frames(el, prefix) {
  for (let i = 0; i < el.frames.length; i++) {
    const name = el.frames[i].name
    console.log(!prefix ? name : prefix + '/' + name)
    print_frames(el.frames[i], child_prefix)
  }
}
window.addEventListener('load', () => {
  print_frames(window)
})

[nicofrand]

I am really afraid this would break websites where iframes are loaded before the links are parsed.
Maybe we could just remove targets for names which are probably invalid like blank or new?