Added support for metal flag to normal map shader.

src/extras/ShaderUtils.js

@@ -473,7 +473,15 @@ THREE.ShaderUtils = {
 
 					"#endif",
 
-					"gl_FragColor.xyz = gl_FragColor.xyz * ( totalDiffuse + ambientLightColor * uAmbientColor) + totalSpecular;",
+					"#ifdef METAL",
+
+						"gl_FragColor.xyz = gl_FragColor.xyz * ( totalDiffuse + ambientLightColor * uAmbientColor + totalSpecular );",
+
+					"#else",
+
+						"gl_FragColor.xyz = gl_FragColor.xyz * ( totalDiffuse + ambientLightColor * uAmbientColor ) + totalSpecular;",
+
+					"#endif",
 
 					"if ( enableReflection ) {",