feat: More obvious loading state when submitting a post (#35153)

app/javascript/mastodon/components/loading_indicator.tsx

@@ -6,15 +6,34 @@ const messages = defineMessages({
   loading: { id: 'loading_indicator.label', defaultMessage: 'Loading…' },
 });
 
-export const LoadingIndicator: React.FC = () => {
+interface LoadingIndicatorProps {
+  /**
+   * Use role='none' to opt out of the current default role 'progressbar'
+   * and aria attributes which we should re-visit to check if they're appropriate.
+   * In Firefox the aria-label is not applied, instead an implied value of `50` is
+   * used as the label.
+   */
+  role?: string;
+}
+
+export const LoadingIndicator: React.FC<LoadingIndicatorProps> = ({
+  role = 'progressbar',
+}) => {
   const intl = useIntl();
 
+  const a11yProps =
+    role === 'progressbar'
+      ? ({
+          role,
+          'aria-busy': true,
+          'aria-live': 'polite',
+        } as const)
+      : undefined;
+
   return (
     <div
       className='loading-indicator'
-      role='progressbar'
-      aria-busy
-      aria-live='polite'
+      {...a11yProps}
       aria-label={intl.formatMessage(messages.loading)}
     >
       <CircularProgress size={50} strokeWidth={6} />