The flag combination --gc-interval=500 --stress-compaction
--stress-flush-bytecode, combined with baking mjsunit.js into the
custom snapshot, caused type feedback for "deepEquals" to be
forgotten, leading to an unexpected soft deopt. Forcing type feedback
collection with %PrepareFunctionForOptimization() fixes that.

Change-Id: I954c7ecbe70ca5b803a5fa7cd809c118f7659f21
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1946347Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65281}