Pass reference instead of shared_ptr to getInspectorDataForInstance

Summary:
changelog: [internal]

This is a pre-condition to get rid of `shared_ptr` from `EventEmitterWrapper`. Also saves us a few copies of shared_ptr, this is negligible though.

Reviewed By: mdvacca

Differential Revision: D31307048

fbshipit-source-id: b84654bed2359b66faf3995795e135e88fe51cb6