[Glitch] Remove isNaN polyfill

Port 169b9c9b13 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/base_polyfills.js

@@ -4,7 +4,6 @@ import 'es6-symbol/implement';
 import includes from 'array-includes';
 import assign from 'object-assign';
 import values from 'object.values';
-import isNaN from 'is-nan';
 import { decode as decodeBase64 } from './utils/base64';
 import promiseFinally from 'promise.prototype.finally';
 
@@ -20,10 +19,6 @@ if (!Object.values) {
   values.shim();
 }
 
-if (!Number.isNaN) {
-  Number.isNaN = isNaN;
-}
-
 promiseFinally.shim();
 
 if (!HTMLCanvasElement.prototype.toBlob) {

app/javascript/flavours/glitch/load_polyfills.js

@@ -15,7 +15,6 @@ function loadPolyfills() {
     Array.prototype.includes &&
     HTMLCanvasElement.prototype.toBlob &&
     window.Intl &&
-    Number.isNaN &&
     Object.assign &&
     Object.values &&
     window.Symbol &&