We want to be consistent with wasdk/wasmparser.

Unnamed function's name would be func#

Doc: https://docs.google.com/document/d/1XoXWONLBgZWQ9dhtoMpQPvD0fnnWA50OorsuSXfME3g
Bug: v8:10242
Change-Id: I12222eef38a57242e9f606007d0ffa76b8e2a4af
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2084052
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Kim-Anh Tran <kimanh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66667}