normal_phong_fragment clean up.

src/renderers/shaders/ShaderChunk/normal_phong_fragment.glsl

@@ -1,4 +1,10 @@
-#ifndef FLAT_SHADED
+#ifdef FLAT_SHADED
+
+	vec3 fdx = dFdx( vViewPosition );
+	vec3 fdy = dFdy( vViewPosition );
+	vec3 normal = normalize( cross( fdx, fdy ) );
+
+#else
 
 	vec3 normal = normalize( vNormal );
 
@@ -8,12 +14,6 @@
 
 	#endif
 
-#else
-
-	vec3 fdx = dFdx( vViewPosition );
-	vec3 fdy = dFdy( vViewPosition );
-	vec3 normal = normalize( cross( fdx, fdy ) );
-
 #endif
 
 #ifdef USE_NORMALMAP
@@ -25,4 +25,3 @@
 	normal = perturbNormalArb( -vViewPosition, normal, dHdxy_fwd() );
 
 #endif
-