Turning the --harmony-array flag on has been delayed behind
unrelated test failures. Now that those tests are disabled,
land the changes.

This patch fixes WebKit tests based on the new change.

R=adamk
LOG=Y
BUG=v8:3578
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1199113003

Cr-Commit-Position: refs/heads/master@{#29209}