More efficient calculation (#24675)

src/lights/LightShadow.js

@@ -75,8 +75,7 @@ class LightShadow {
 			0.0, 0.0, 0.0, 1.0
 		);
 
-		shadowMatrix.multiply( shadowCamera.projectionMatrix );
-		shadowMatrix.multiply( shadowCamera.matrixWorldInverse );
+		shadowMatrix.multiply( _projScreenMatrix );
 
 	}