Reuses (and renames) the SFI "mark for optimization" flag to also permit
marking for baseline recompilation. The flag now represents a "tier up"
request, and CompileLazy can get baseline code as well as optimized
code.

BUG=v8:5512

Review-Url: https://codereview.chromium.org/2448933002
Cr-Commit-Position: refs/heads/master@{#40612}