docs(\$sniffer): fix minor typo

Closes angular#5544

Author: Tiago Ribeiro

src/ng/sniffer.js

@@ -59,7 +59,7 @@ function $SnifferProvider() {
       // http://code.google.com/p/android/issues/detail?id=17471
       // https://github.com/angular/angular.js/issues/904
 
-      // older webit browser (533.9) on Boxee box has exactly the same problem as Android has
+      // older webkit browser (533.9) on Boxee box has exactly the same problem as Android has
       // so let's not use the history API also
       // We are purposefully using `!(android < 4)` to cover the case when `android` is undefined
       // jshint -W018