We added %PrepareForOptimization, that holds the bytecode array strongly until the
function is optimized, to test using assertOptimized. This function expects that the
function is optimized before preparing the next function for optimization. In some
tests, we may not explicitly optimize a function because it got inlined into other
functions or if it was already optimized. This cl relaxes this condition and holds
onto multiple bytecode arrays.

Bug: v8:8801, v8:8395
Change-Id: Iebccc4a798aa3f35be9ee295eb3c4917da659c22
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1541055Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60552}