Would cause UNREACHABLE to be triggered if target was invalid, and INVALID_VALUE to
be returned instead of INVALID_ENUM if it were the only erroneous argument.

Change-Id: I2606e77379fa2832a50b3a299e6474a4b2f68afa
Reviewed-on: https://chromium-review.googlesource.com/189701Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Shannon Woods <shannonwoods@chromium.org>