Revert: WebGLShadowMap: Removed skinning reference.

src/renderers/webgl/WebGLShadowMap.js

@@ -82,6 +82,7 @@ function WebGLShadowMap( _renderer, _lights, _objects, capabilities ) {
 			vertexShader: distanceShader.vertexShader,
 			fragmentShader: distanceShader.fragmentShader,
 			morphTargets: useMorphing,
+			skinning: useSkinning,
 			clipping: true
 		} );