The 'done' setting dance in BuildFillArrayWithIterator turned out to
not be useful, as the StoreInArrayLiteral call could not ever throw an
exception. Since iterator exceptions count as done, we are guarnteed to
be done as soon as we enter the loop.

Change-Id: Ibe2ba1fcbe383bfcfedb185169890b6931cc7884
Reviewed-on: https://chromium-review.googlesource.com/c/1402792
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58695}