Fix page getting stuck in Foliate GTK

paginator.js

@@ -607,6 +607,13 @@ export class Paginator extends HTMLElement {
         // FIXME: vertical-rl only, not -lr
         if (this.scrolled && this.#vertical) offset = -offset
         if (smooth && this.pageAnimation) return new Promise((resolve, reject) => {
+            // `requestAnimationFrame` fixes the whole page getting "stuck" when
+            // transitioning chapters in Foliate (the GTK 4 app).
+            // It happens often but not always, and resolves itself after
+            // interacting with the page (e.g. clicking on it).
+            // IDK what causes it and I can't reproduce it in any other browser
+            // or even with a WebKitGTK WebView, but this trick seems to fix it
+            requestAnimationFrame(() => {
                 try {
                     const onScroll = () => {
                         if (Math.abs(element[scrollProp] - offset) > 2) return
@@ -621,6 +628,7 @@ export class Paginator extends HTMLElement {
                     reject(e)
                 }
             })
+        })
         else {
             element[scrollProp] = offset
             this.#afterScroll(reason)