Currently, the CodeMap utilizes double indirection into a deque for
entries in its map. Since we don't reuse CodeEntry objects, this doesn't
confer any benefits really -- avoid this step and save memory by
maintaining only a single mapping.

Bug: v8:11054
Change-Id: I2cbc188ff64dd2faa9c4c03d9892b4c8e5e68794
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2617746Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Andrew Comminos <acomminos@fb.com>
Cr-Commit-Position: refs/heads/master@{#72019}