PointLightShadow: Clean up.

src/lights/PointLightShadow.js

@@ -64,7 +64,6 @@ PointLightShadow.prototype = Object.assign( Object.create( LightShadow.prototype
 			shadowMatrix = this.matrix,
 			lightPositionWorld = this._lightPositionWorld,
 			lookTarget = this._lookTarget,
-			shadowMatrix = this.matrix,
 			projScreenMatrix = this._projScreenMatrix;
 
 		lightPositionWorld.setFromMatrixPosition( light.matrixWorld );