Update variable name

Author: ChenX

examples/webgl_tonemapping.html

@@ -74,7 +74,7 @@
 				Reinhard: THREE.ReinhardToneMapping,
 				Uncharted2: THREE.Uncharted2ToneMapping,
 				Cineon: THREE.CineonToneMapping,
-				ACESFilm: THREE.ACESFilmicToneMapping
+				ACESFilmic: THREE.ACESFilmicToneMapping
 			};
 
 			var camera, scene, renderer, group;