Purged gd still passes Lib.isPlotDiv

[rreusser]

If gd was ever a plot, then Lib.isPlotDiv(Plotly.purge(gd)) === true still passes. The solution would be for Plotly.purge() to remove the js-plotly-plot class added here.

The conclusion at the moment is not to fix this with a breaking change, but it seems to be a bug nonetheless.

[gvwilson]

Hi - this issue has been sitting for a while, so as part of our effort to tidy up our public repositories I'm going to close it. If it's still a concern, we'd be grateful if you could open a new issue (with a short reproducible example if appropriate) so that we can add it to our stack. Cheers - @gvwilson