Compiled irregexp code should be cleared unless
FunctionCodeHandling::kKeep is passed.

Bug: v8:8572
Change-Id: Icb74cc6e0f39a69f8383b05f1638cf0e3be1807c
Reviewed-on: https://chromium-review.googlesource.com/c/1373773
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58272}