Refactor shouldUpdateScroll stuff

app/javascript/flavours/glitch/containers/scroll_container.js

@@ -0,0 +1,15 @@
+import { ScrollContainer as OriginalScrollContainer } from 'react-router-scroll-4';
+
+// ScrollContainer is used to automatically scroll to the top when pushing a
+// new history state and remembering the scroll position when going back.
+// There are a few things we need to do differently, though.
+const defaultShouldUpdateScroll = (prevRouterProps, { location }) => {
+  return !(prevRouterProps?.location?.state?.mastodonModalKey || location.state?.mastodonModalKey);
+}
+
+export default
+class ScrollContainer extends OriginalScrollContainer {
+  static defaultProps = {
+    shouldUpdateScroll: defaultShouldUpdateScroll,
+  };
+}