Summary:
Replaces the use of `framesToPop` in `_allocateCallback` (in `__DEV__` only) with statically accessing the second frame of the stack.
Changelog: [Internal]
Reviewed By: cpojer
Differential Revision: D17877261
fbshipit-source-id: 8e4d0eb2ed7984b66a99752fb21f7909474fda8f