[Popover] Unreasonable complex selectors with duplicate classes generated

[Westbrook]

https://github.com/adobe/spectrum-css/blob/3c7de5e07d34ca6ca1ae873ff32f4e7a02d1f0ad/components/popover/index.css#L319-L346

This will generate selectors like .spectrum-Popover--withTip.spectrum-Popover--left.spectrum-Popover--left .spectrum-Popover-tip wherein the spectrum-Popover--left is duplicated.

Can this be smoothed out? It creates additional difficult when processing the output downstream.

[pfulton]

Tracking this in Jira via CSS-750