- Reworks it to use a builtin to GetProperty, after making sure it's
  an "own" property. This reduces the size of the builtin by 2/3 (from
  1476 to 596 bytes on x64).

Change-Id: I41c1642369f73e5322790f3091b8cea9a650a529
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2181642Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67693}