Fix renderer test

Author: vincentfretin

tests/core/scene/a-scene.test.js

@@ -76,7 +76,9 @@ suite('a-scene (without renderer) - WebXR', function () {
       // Mock renderer.
       assert.ok(sceneEl.renderer);
       // Mock renderer is not a real WebGLRenderer.
-      assert.notOk(sceneEl.renderer instanceof THREE.WebGLRenderer);
+      assert.notOk(
+          (THREE.WebGLRenderer && sceneEl.renderer instanceof THREE.WebGLRenderer) ||
+          (THREE.WebGPURenderer && sceneEl.renderer instanceof THREE.WebGPURenderer));
     });
   });