Simplify implementation of PlaneHelper (#24378)
Simplify implementation of PlaneHelper (#24378)

* Simplify implementation of PlaneHelper

* Remove unnecessary include file
mrdoob/three.js,makc/three.js.fork,aardgoose/three.js,mrdoob/three.js,WestLangley/three.js,aardgoose/three.js,06wj/three.js,makc/three.js.fork,gero3/three.js,06wj/three.js,gero3/three.js,WestLangley/three.js