Examples: Clean up. (#23276)

examples/webgl_furnace_test.html

@@ -107,21 +107,15 @@
 
 			function createEnvironment() {
 
-				return new Promise( function ( resolve ) {
+				const envScene = new THREE.Scene();
+				envScene.background = new THREE.Color( COLOR );
+				if ( renderer.outputEncoding === THREE.sRGBEncoding ) envScene.background.convertSRGBToLinear();
 
-					const envScene = new THREE.Scene();
-					envScene.background = new THREE.Color( COLOR );
-					if ( renderer.outputEncoding === THREE.sRGBEncoding ) envScene.background.convertSRGBToLinear();
+				const pmremGenerator = new THREE.PMREMGenerator( renderer );
+				radianceMap = pmremGenerator.fromScene( envScene ).texture;
+				pmremGenerator.dispose();
 
-					const pmremGenerator = new THREE.PMREMGenerator( renderer );
-					radianceMap = pmremGenerator.fromScene( envScene ).texture;
-					pmremGenerator.dispose();
-
-					scene.background = radianceMap;
-
-					resolve();
-
-				} );
+				scene.background = radianceMap;
 
 			}