Instead of calling Abort, which was failing when trying to read its
string argument as a Smi.

Change-Id: I008b8620cbb7df2a56fc5c5ea42f4d573b159f76
Reviewed-on: https://chromium-review.googlesource.com/856778Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50431}