Revert "tutorial: remove unnecessary call performance.now() inside raf"

This reverts commit 159cf86df6.

site/content/tutorial/06-bindings/12-bind-this/app-a/App.svelte

@@ -5,9 +5,9 @@
 
 	onMount(() => {
 		const ctx = canvas.getContext('2d');
-		let frame = requestAnimationFrame(loop);
+		let frame;
 
-		function loop(t) {
+		(function loop() {
 			frame = requestAnimationFrame(loop);
 
 			const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
@@ -17,6 +17,8 @@
 				const x = i % canvas.width;
 				const y = i / canvas.height >>> 0;
 
+				const t = window.performance.now();
+
 				const r = 64 + (128 * x / canvas.width) + (64 * Math.sin(t / 1000));
 				const g = 64 + (128 * y / canvas.height) + (64 * Math.cos(t / 1000));
 				const b = 128;
@@ -28,7 +30,7 @@
 			}
 
 			ctx.putImageData(imageData, 0, 0);
-		}
+		}());
 
 		return () => {
 			cancelAnimationFrame(frame);

site/content/tutorial/06-bindings/12-bind-this/app-b/App.svelte

@@ -5,9 +5,9 @@
 
 	onMount(() => {
 		const ctx = canvas.getContext('2d');
-		let frame = requestAnimationFrame(loop);
+		let frame;
 
-		function loop(t) {
+		(function loop() {
 			frame = requestAnimationFrame(loop);
 
 			const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
@@ -17,6 +17,8 @@
 				const x = i % canvas.width;
 				const y = i / canvas.height >>> 0;
 
+				const t = window.performance.now();
+
 				const r = 64 + (128 * x / canvas.width) + (64 * Math.sin(t / 1000));
 				const g = 64 + (128 * y / canvas.height) + (64 * Math.cos(t / 1000));
 				const b = 128;
@@ -28,7 +30,7 @@
 			}
 
 			ctx.putImageData(imageData, 0, 0);
-		}
+		}());
 
 		return () => {
 			cancelAnimationFrame(frame);