Trying to reduce use of our self-baked data structures.

Bug: v8:7570
Change-Id: I419a932b6b8904810844d40a5636e423df832197
Reviewed-on: https://chromium-review.googlesource.com/1032739
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53033}