InterpreterEntryTrampoline checks
1. If there is any optimization marker, and process the marker by
calling the correct runtime function
2. If there is any optimized code, it installs optimized code and starts
executing optimized code.

Earlier it was OK to do these two checks in any order, since it wasn't
possible that we have both a marker and optimized code. Turboprop code
calls out to IET to process the optimization marker / install next tier
optimized code. So we have to check for optimization marker before we
check for optimized code.

Bug: v8:9684
Change-Id: Iaefb51aec9c2de0bcbacbdbd8a5dff513e573036
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2505721Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70914}