[Glitch] Fix old browsers crashing because of missing `finally` polyfill in web UI

Port 3cdaa34783 to glitch-soc

Signed-off-by: Thibaut Girka <thib@sitedethib.com>

app/javascript/flavours/glitch/util/base_polyfills.js

@@ -6,6 +6,7 @@ import assign from 'object-assign';
 import values from 'object.values';
 import isNaN from 'is-nan';
 import { decode as decodeBase64 } from './base64';
+import promiseFinally from 'promise.prototype.finally';
 
 if (!Array.prototype.includes) {
   includes.shim();
@@ -23,6 +24,8 @@ if (!Number.isNaN) {
   Number.isNaN = isNaN;
 }
 
+promiseFinally.shim();
+
 if (!HTMLCanvasElement.prototype.toBlob) {
   const BASE64_MARKER = ';base64,';
 

app/javascript/flavours/glitch/util/load_polyfills.js

@@ -18,7 +18,8 @@ function loadPolyfills() {
     Number.isNaN &&
     Object.assign &&
     Object.values &&
-    window.Symbol
+    window.Symbol &&
+    Promise.prototype.finally
   );
 
   // Latest version of Firefox and Safari do not have IntersectionObserver.