Remove IE polyfillsfrom the Blitz inject script

Removes dependency on `polyfill.io`, which was recently sold.
https://twitter.com/triblondon/status/1761852117579427975

CHANGELOG.md

@@ -1,6 +1,8 @@
 # Release Notes for Blitz
 
-## 4.12.0 - Unreleased
+## 4.12.0 - 2024-02-27
+
+> {warning} Polyfills for IE have been removed from the Blitz inject script. If you need to support IE, you will need to add the polyfills yourself.
 
 ### Added
 
@@ -14,6 +16,9 @@
 - Optimised the params that are stored on tracked element queries. 
 - Made the ordering of items displayed in the Blitz diagnostics utility deterministic.
 
+### Removed
+
+- Removed the `fetch`, `Promise` and `CustomEvent` polyfills for IE from the Blitz inject script, as they were pulling from `polyfill.io`. If you need to support IE, you will need to add the polyfills to your templates yourself.
 
 ## 4.11.2 - 2024-02-19
 

src/variables/BlitzVariable.php

@@ -17,7 +17,6 @@
 use putyourlightson\blitz\services\CacheRequestService;
 use Twig\Markup;
 use yii\web\NotFoundHttpException;
-use yii\web\View as BaseView;
 
 class BlitzVariable
 {
@@ -296,15 +295,6 @@ private function _getScript(string $uri, array $params, VariableConfigModel $con
             }
         }
 
-        // Create polyfills using https://polyfill.io/v3/url-builder/.
-        $polyfills = ['fetch', 'Promise', 'CustomEvent'];
-        $polyfillUrl = 'https://polyfill.io/v3/polyfill.min.js?features=' . implode('%2C', $polyfills);
-
-        // Register polyfills for IE11 only, using the `module/nomodule` pattern.
-        // https://3perf.com/blog/polyfills/#modulenomodule
-        $view->registerJsFile($polyfillUrl, ['nomodule' => true]);
-        $view->registerJs($js, BaseView::POS_END);
-
         $this->_injected++;
         $id = $this->_injected;