GizmoHelper preserveDrawingBuffer stops frame clear

[marks311]

When using a GizmoHelper and setting the gl preserveDrawingBuffer to true, the Helper stops all canvas Elements from clearing the last frames.
minimal setup Sandbox example: https://codesandbox.io/embed/flamboyant-rgb-d3lrx

[joshuaellis]

GizmoHelper came in as a contribution, as such we'll need the community to resolve issues like this. Thank you for the report!