shadowmap_pars_vertex: removed unused reference.

src/renderers/shaders/ShaderChunk/shadowmap_pars_vertex.glsl

@@ -1,7 +1,6 @@
 #ifdef USE_SHADOWMAP
 
-	uniform float shadowDarkness[ NUM_SHADOWS ];
 	uniform mat4 shadowMatrix[ NUM_SHADOWS ];
 	varying vec4 vShadowCoord[ NUM_SHADOWS ];
 
-#endif
+#endif