Restore infinite resize detection (chartjs#6011)

src/platform/platform.dom.js

@@ -155,11 +155,8 @@ function fromNativeEvent(event, chart) {
 
 function throttled(fn, thisArg) {
 	let ticking = false;
-	let args = [];
-
-	return function(...rest) {
-		args = Array.prototype.slice.call(rest);
 
+	return function(...args) {
 		if (!ticking) {
 			ticking = true;
 			helpers.requestAnimFrame.call(window, () => {
@@ -178,11 +175,24 @@ function throttled(fn, thisArg) {
  * @return {ResizeObserver}
  */
 function watchForResize(element, fn) {
+	const resize = throttled((width, height) => {
+		const w = element.clientWidth;
+		fn(width, height);
+		if (w < element.clientWidth) {
+			// If the container size shrank during chart resize, let's assume
+			// scrollbar appeared. So we resize again with the scrollbar visible -
+			// effectively making chart smaller and the scrollbar hidden again.
+			// Because we are inside `throttled`, and currently `ticking`, scroll
+			// events are ignored during this whole 2 resize process.
+			// If we assumed wrong and something else happened, we are resizing
+			// twice in a frame (potential performance issue)
+			fn();
+		}
+	}, window);
+
 	const observer = new ResizeObserver(entries => {
 		const entry = entries[0];
-		helpers.requestAnimFrame.call(window, () => {
-			fn(entry.contentRect.width, entry.contentRect.height);
-		});
+		resize(entry.contentRect.width, entry.contentRect.height);
 	});
 	observer.observe(element);
 	return observer;