Fix GridHelper API change (#8812)

examples/misc_sound.html

@@ -156,9 +156,7 @@
 
 				// ground
 
-				var helper = new THREE.GridHelper( 500, 10 );
-				helper.color1.setHex( 0x444444 );
-				helper.color2.setHex( 0x444444 );
+				var helper = new THREE.GridHelper( 500, 10, 0x444444, 0x444444 );
 				helper.position.y = 0.1;
 				scene.add( helper );