GridHelper clone is broken

[makc]

it has constructor = THREE.GridHelper but inherited clone method expects constructor property to be LineSegments

[makc]

btw, this can be fixed by adding GridHelper's own clone if my other request #8451 is granted ) or by having clone on instance, not the prototype

[Mugen87]

Because #15981 was reverted, cloning a GridHelper applies wrong arguments to the ctor again.

[Mugen87]

GridHelper should maybe look more like in this fiddle so it's easier to copy/clone and serialize/deserialize it: https://jsfiddle.net/kjb46s8y/