When the intention is to handle every case, *and* when we can be
reasonably sure that no invalid enum values will occur (e.g. from
reading untrusted data), then we shouldn't have a "default:" case
in a switch statement so that the compiler will warn us when a
case is missing.

Bug: v8:10506
Change-Id: Iefdebd54802611e7ec3479afa3c4e6506f97a095
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2204284
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67854}