Isolating a trace makes visible:false traces visible:legendonly

[rreusser]

Expected: isolating a trace preserves visible: false status of hidden traces

Observed: isolating a trace changes visible: false traces to legendonly

Version: plotly-latest.js

See: https://codepen.io/rsreusser/pen/qPZNqo

I think the fix is straightforward. Seeking confirmation on expected behavior.

[etpinard]

Expected: isolating a trace preserves visible: false status of hidden traces

I agree 100%.

[rreusser]

Thanks! Fixing that along with the groupby fixes.

[etpinard]

done in #2022