A human-readable name is in Blink only available for C++ types with
JS wrapper objects and for manually annotated types that are interesting
for the snapshot. Return the proper C++ shallow size of the object in
this case. (Merge nodes will have their JS+C++ sizes added.)

Bug: chromium:1228411, chromium:1056170
Change-Id: Ib2b1b7b9dec80e5cccccb1aad8c4c035715612ec
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3021169Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75698}