Back out "DispatchKeySet perf improvements"
Summary: D34018849
Test Plan: D34018849
Reviewed By: shoumikhin
Differential Revision: D34018840
fbshipit-source-id: a78e3ea5b8ac93e9e002e2583961fd3a545a0abd
(cherry picked from commit 57b7c51f74960025a7c0af26be9aa1fa08fa6f7f)
