not all the new window target is _blank

[jcyuan]

nextjs-toploader/src/index.tsx

Line 244 in 461a78d

const isExternalLink = (anchor as HTMLAnchorElement).target === '_blank';

this line has bug, because i can set my link as <a href="/page" target="_rules" /> so that all the links with this target won't open too many new windows and they will be opened in the same new window, _rules is like a target window name.

now all my '_rules' links will trigger the progress bar to show.