TiltLoader: Use webp for textures.

examples/jsm/loaders/TiltLoader.js

@@ -380,7 +380,7 @@ const loader = new TextureLoader().setPath( './textures/tiltbrush/' );
 const shaders = {
 	'Light': {
 		uniforms: {
-			mainTex: { value: loader.load( 'Light.png' ) },
+			mainTex: { value: loader.load( 'Light.webp' ) },
 			alphaTest: { value: 0.067 },
 			emission_gain: { value: 0.45 },
 			alpha: { value: 1 },