* Implement support for `drop-shadow`
* Clean up remnant from early attempts
* Fix misleading comments on GenericSimpleShadow
If Servo-specific `style` changes will need to be upstreamed anyway, I might as well fix a thing that had thrown me off!
* Revert "Fix misleading comments on GenericSimpleShadow"
This reverts commit cdc810b826ac082041adc212c24649ee3b86ca0a.
* Clean up an import
* Update test expectations
* Fix missing expectation on Layout 2013