[Bug] symbolUtils, renderPreviewHTML and simple-fill

[NicholasWright]

For simple fills, for anything other than `solid` types, the preview doesn't render anything, and in the console, the arcgis internal "previewSymbol2D.js" throws an error against ".toCss is not a function".

Relevant Codepen, testing on the `/next/` version (also tested against 4.24): 

https://codepen.io/Tickthokk/pen/oNdwoEv

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It'd be great to render polygons that are not solid!

Thank you 🙂

[AnneFitz · Accepted solution]

Hi @NicholasWright - this works as expected if you use the SimpleFillSymbol constructor instead of autocasting. Here's an updated version of your example: https://codepen.io/annefitz/pen/yLjXvgO

Hope this helps!