The two projects are independent; work on Electrolysis (multi-process Firefox) actually predates Servo. Old versions of mobile Firefox used Electrolysis, for e

The two projects are independent; work on Electrolysis (multi-process Firefox) actually predates Servo. Old versions of mobile Firefox used Electrolysis, for example. But converting desktop Firefox and supporting its whole add-on ecosystem is a huge project, and was also put on hold for a long time.