... by reading the |map_index| value from the SharedFunctionInfo's
|compiler_hints| field directly.

Bug: v8:6459
Change-Id: I32c4c903b16fa9f7e7da755667dadef7fadfc5e0
Reviewed-on: https://chromium-review.googlesource.com/531024
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45871}