why buggyfill do fill on ios10 and ios10+

when I search in caniuse: https://caniuse.com/#search=viewport viewport units wokrs find on iOS8 and iOS8+

and I found that, the comment is also said:

var isMobileSafari = /(iPhone|iPod|iPad).+AppleWebKit/i.test(userAgent) && (function() {
      // Regexp for iOS-version tested against the following userAgent strings:
      // Example WebView UserAgents:
      // * iOS Chrome on iOS8: "Mozilla/5.0 (iPad; CPU OS 8_1 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) CriOS/39.0.2171.50 Mobile/12B410 Safari/600.1.4"
      // * iOS Facebook on iOS7: "Mozilla/5.0 (iPhone; CPU iPhone OS 7_1_1 like Mac OS X) AppleWebKit/537.51.2 (KHTML, like Gecko) Mobile/11D201 [FBAN/FBIOS;FBAV/12.1.0.24.20; FBBV/3214247; FBDV/iPhone6,1;FBMD/iPhone; FBSN/iPhone OS;FBSV/7.1.1; FBSS/2; FBCR/AT&T;FBID/phone;FBLC/en_US;FBOP/5]"
      // Example Safari UserAgents:
      // * Safari iOS8: "Mozilla/5.0 (iPhone; CPU iPhone OS 8_0 like Mac OS X) AppleWebKit/600.1.3 (KHTML, like Gecko) Version/8.0 Mobile/12A4345d Safari/600.1.4"
      // * Safari iOS7: "Mozilla/5.0 (iPhone; CPU iPhone OS 7_0 like Mac OS X) AppleWebKit/537.51.1 (KHTML, like Gecko) Version/7.0 Mobile/11A4449d Safari/9537.53"
      var iOSversion = userAgent.match(/OS (\d+)/);
      // viewport units work fine in mobile Safari and webView on iOS 8+
      return iOSversion && iOSversion.length > 1 && parseInt(iOSversion[1]) < 10;
    })();

but why the return valud satement detect as iOS10-.

I think this would cost some unused works on iOS8+

rodneyrehm / viewport-units-buggyfill

why buggyfill do fill on ios10 and ios10+ #101