Fix Camera pointer

src/Cameras/Inputs/babylon.arcRotateCameraPointersInput.ts

@@ -281,7 +281,7 @@ module BABYLON {
                 }
             }
 
-            this._observer = this.camera.getScene().onPointerObservable.add(this._pointerInput, PointerEventTypes.POINTERDOWN | PointerEventTypes.POINTERUP | PointerEventTypes.POINTERMOVE | PointerEventTypes._POINTERDOUBLETAP);
+            this._observer = this.camera.getScene().onPointerObservable.add(this._pointerInput, PointerEventTypes.POINTERDOWN | PointerEventTypes.POINTERUP | PointerEventTypes.POINTERMOVE | PointerEventTypes.POINTERDOUBLETAP);
 
             this._onContextMenu = evt => {
                 evt.preventDefault();