Remove isOldIE check in tests

test/specs/__helpers.js

@@ -11,9 +11,6 @@ axios = require('../../index');
 jasmine.DEFAULT_TIMEOUT_INTERVAL = 20000;
 jasmine.getEnv().defaultTimeoutInterval = 20000;
 
-// Is this an old version of IE that lacks standard objects like DataView, ArrayBuffer, FormData, etc.
-isOldIE = /MSIE (8|9)\.0/.test(navigator.userAgent);
-
 // Get Ajax request using an increasing timeout to retry
 getAjaxRequest = (function () {
 var attempts = 0;