Remove unused left over VR HELPER

src/babylon.scene.ts

@@ -904,13 +904,6 @@
             return this._mainSoundTrack;
         }
 
-        /**
-         * Gets or sets the VRExperienceHelper attached to the scene
-         * @see http://doc.babylonjs.com/how_to/webvr_helper
-         * @ignorenaming
-         */
-        public VRHelper: VRExperienceHelper;
-
         // Private
         private _engine: Engine;
 
@@ -4841,11 +4834,6 @@
                 this.disposeSounds();
             }
 
-            // VR Helper
-            if (this.VRHelper) {
-                this.VRHelper.dispose();
-            }
-
             // Detach cameras
             var canvas = this._engine.getRenderingCanvas();