They are never used, and can't really be TNodified since they are
not a value output in any case.

BUG=v8:6949,v8:11074

Change-Id: Id6f5807247c6fe53fb12dce9e2cfc66b5a046398
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2532305
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Auto-Submit: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71133}