Fix -[FBFramebuffer jsonSerializableRepresentation] Crash
Fix -[FBFramebuffer jsonSerializableRepresentation] Crash

Summary: This fails on the `IOSurface` variant and shouldn't

Reviewed By: marekcirkos

Differential Revision: D4698403

fbshipit-source-id: e227c02418f3fa36c641209db2c42de2cce61d19

facebook/FBSimulatorControl,facebook/FBSimulatorControl,StevenUpForever/FBSimulatorControl,plu/FBSimulatorControl,plu/FBSimulatorControl,facebook/FBSimulatorControl,StevenUpForever/FBSimulatorControl,plu/FBSimulatorControl,StevenUpForever/FBSimulatorControl,plu/FBSimulatorControl,facebook/FBSimulatorControl,StevenUpForever/FBSimulatorControl,facebook/FBSimulatorControl