/*!
{
  "name": "History API",
  "property": "history",
  "caniuse": "history",
  "tags": ["history"],
  "authors": ["Hay Kranen", "Alexander Farkas"],
  "notes": [{
    "name": "W3C Spec",
    "href": "https://www.w3.org/TR/html51/browsers.html#the-history-interface"
  }, {
    "name": "MDN Docs",
    "href": "https://developer.mozilla.org/en-US/docs/Web/API/window.history"
  }],
  "polyfills": ["historyjs", "html5historyapi"]
}
!*/
/* DOC
Detects support for the History API for manipulating the browser session history.
*/
define(['Modernizr'], function(Modernizr) {
  Modernizr.addTest('history', function() {
    // Issue #733
    // The stock browser on Android 2.2 & 2.3, and 4.0.x returns positive on history support
    // Unfortunately support is really buggy and there is no clean way to detect
    // these bugs, so we fall back to a user agent sniff :(
    var ua = navigator.userAgent;

    // We only want Android 2 and 4.0, stock browser, and not Chrome which identifies
    // itself as 'Mobile Safari' as well, nor Windows Phone (issue #1471).
    if ((ua.indexOf('Android 2.') !== -1 ||
        (ua.indexOf('Android 4.0') !== -1)) &&
        ua.indexOf('Mobile Safari') !== -1 &&
        ua.indexOf('Chrome') === -1 &&
        ua.indexOf('Windows Phone') === -1 &&
    // Since all documents on file:// share an origin, the History apis are
    // blocked there as well
        location.protocol !== 'file:'
    ) {
      return false;
    }

    // Return the regular check
    return (window.history && 'pushState' in window.history);
  });
});

@@ -896,16 +896,181 @@
 erAgent;
+%0A    %0A    // Some browsers allow to have empty userAgent.%0A    // Therefore, we need to check ua before using %22indexOf%22 on it.%0A    if(!ua) %7B%0A      return false;%0A    %7D
 %0A%0A    //

Check if userAgent is empty (#2471)