Use helpers to check environment in frontend (#27633)

app/javascript/mastodon/performance.js

@@ -5,7 +5,9 @@
 
 import * as marky from 'marky';
 
-if (process.env.NODE_ENV === 'development') {
+import { isDevelopment } from './utils/environment';
+
+if (isDevelopment()) {
   if (typeof performance !== 'undefined' && performance.setResourceTimingBufferSize) {
     // Increase Firefox's performance entry limit; otherwise it's capped to 150.
     // See: https://bugzilla.mozilla.org/show_bug.cgi?id=1331135
@@ -18,13 +20,13 @@ if (process.env.NODE_ENV === 'development') {
 }
 
 export function start(name) {
-  if (process.env.NODE_ENV === 'development') {
+  if (isDevelopment()) {
     marky.mark(name);
   }
 }
 
 export function stop(name) {
-  if (process.env.NODE_ENV === 'development') {
+  if (isDevelopment()) {
     marky.stop(name);
   }
 }