Summary:
The current Popover component isn't compatible with the new (in progress) component library because it relies on overflowing container elements, which isn't allowed in the generic Layout component.
So this is a new Popover element, which uses absolute positioning instead. It takes heavy inspiration from the Tooltip and TooltipProvider components which do a similar thing.
Still to do:
[x] Edge cases when popover would be near a window edge
[x] Style it to look nice
[x] Split the use case (RatingButton) changes into a separate diff
[x] When the location of the popover container moves (the rating button in this case, e.g. if you resize the window), it doesn't currently cause the effect function in the popover, so it doesn't get moved when it should
[x] Add a little pointer thingy like a speech bubble
[x] Make sure it's perfectly positioned
[ ] Rename it to Popover and delete the old one. Not done, since it's just a stopgap.
Reviewed By: mweststrate
Differential Revision: D22693105
fbshipit-source-id: bc141433914bc20da48f8ae96764a95f7cd74ce5
d7a6356fb6