Examples: Fix webgl_worker_offscreencanvas.

examples/jsm/offscreen/scene.js

@@ -1,4 +1,4 @@
-import * as THREE from 'three';
+import * as THREE from '../../../build/three.module.js';
 
 var camera, scene, renderer, group;
 

examples/webgl_worker_offscreencanvas.html

@@ -68,14 +68,6 @@
 		<!-- Remove this when import maps will be widely supported -->
 		<script async src="https://unpkg.com/[email protected]/dist/es-module-shims.js"></script>
 
-		<script type="importmap">
-			{
-				"imports": {
-					"three": "../build/three.module.js"
-				}
-			}
-		</script>
-
 		<script type="module">
 
 			import initJank from './jsm/offscreen/jank.js';