stop setting canvas width/height on every draw, it clears the canvas

src/sketch.js

@@ -63,9 +63,6 @@ export default class Sketch {
 	}
 
 	render (now) {
-		this.canvas.width = this.container.offsetWidth;
-		this.canvas.height = this.container.offsetHeight;
-
 		this.context.lastUTC = this.context.utc || null;
 		this.context.utc = Date.now();