The CommandlineAPI destructor retrieves the property descriptors for
every function it installed on the global object, but it doesn't do
anything with the descriptor directly, just verifies that it could
retrieve them.

As there are cases where 'getOwnPropertyDescriptor' can actually fail,
such as stack overflow or termination exceptions, we remove the check.

R=yangguo@chromium.org

Bug: chromium:914286
Change-Id: I01147195bdf107131de602789f448abe0afa6b0e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2516470
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70939}