&vector[i] is invalid unless 0 <= i < vector.size(). This means:

- &vector[0] is invalid if the vector is empty.

- &vector[vector.size()] is not a valid way to point past the end of the
  vector.

Fix these to use vector.data() + vector.size() which is the defined to
get begin and end pointers for a vector.

Bug: chromium:1027059
Change-Id: Ife1f0e64807b32ebdca66dba8ffc206d90a0de75
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1929071
Auto-Submit: David Benjamin <davidben@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65091}