Drive-by-fix: increase coverage in object literals test.

Change-Id: Iccfdf35b29229f63b3e8c1d961bee56ee03da688
Reviewed-on: https://chromium-review.googlesource.com/751661Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49105}