ArrayList is a FixedArray where kFirstIndex is > 0. The
Elements() methods returns a copy of the elements starting at
kFirstIndex, i.e., without the length that is stored in the first
slot.

Drive-by fix: Rename some variables.

BUG=

Change-Id: Ia1de73c4780a179301007f2ab9080fd08e8ea99d
Reviewed-on: https://chromium-review.googlesource.com/466186Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Franziska Hinkelmann <franzih@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44365}