Use integer canvas dimensions

As a result of #12097, the HTMLCanvasElement's `width` and `height` (which are always integers - see [MDN][1]) may be compared to fractional `deviceWidth` and `deviceHeight`, resulting in extra resize and update events being fired.

This PR rounds the dimensions for purposes of comparing to the canvas element's, which should put the behavior closer to Chart.js 4.5.0 and earlier.

I've tested this against #11224, my own code (which was generating errors due to an interaction between these extra events and some internal plugins), and https://codepen.io/joshkel/pen/azdjLGZ, and it seems to work.

[1]: https://developer.mozilla.org/en-US/docs/Web/API/HTMLCanvasElement#instance_properties

Author: joshkel

src/helpers/helpers.dom.ts

@@ -227,12 +227,14 @@ export function retinaScale(
     canvas.style.width = `${chart.width}px`;
   }
 
+  const canvasHeight = Math.floor(deviceHeight);
+  const canvasWidth = Math.floor(deviceWidth);
   if (chart.currentDevicePixelRatio !== pixelRatio
-      || canvas.height !== deviceHeight
-      || canvas.width !== deviceWidth) {
+      || canvas.height !== canvasHeight
+      || canvas.width !== canvasWidth) {
     (chart as PrivateChart).currentDevicePixelRatio = pixelRatio;
-    canvas.height = deviceHeight;
-    canvas.width = deviceWidth;
+    canvas.height = canvasHeight;
+    canvas.width = canvasWidth;
     chart.ctx.setTransform(pixelRatio, 0, 0, pixelRatio, 0, 0);
     return true;
   }