Prevent infinite resize when vertical scrollbar appears (#6011)

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)

Author: kurkle

src/core/core.controller.js

@@ -277,13 +277,13 @@ helpers.extend(Chart.prototype, /** @lends Chart */ {
 			plugins.notify(me, 'resize', [newSize]);
 
 			// Notify of resize
-			if (me.options.onResize) {
-				me.options.onResize(me, newSize);
+			if (options.onResize) {
+				options.onResize(me, newSize);
 			}
 
 			me.stop();
 			me.update({
-				duration: me.options.responsiveAnimationDuration
+				duration: options.responsiveAnimationDuration
 			});
 		}
 	},

src/platforms/platform.dom.js

@@ -273,7 +273,19 @@ function addResizeListener(node, listener, chart) {
 	// Let's keep track of this added resizer and thus avoid DOM query when removing it.
 	var resizer = expando.resizer = createResizer(throttled(function() {
 		if (expando.resizer) {
-			return listener(createEvent('resize', chart));
+			var container = chart.options.maintainAspectRatio && node.parentNode;
+			var w = container ? container.clientWidth : 0;
+			listener(createEvent('resize', chart));
+			if (container && container.clientWidth < w && chart.canvas) {
+				// 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)
+				listener(createEvent('resize', chart));
+			}
 		}
 	}));