MSVC seems to instantiate the Parser::PreParserIdentifierToAstRawString
method despite it being unused. This CL adds an (unreachable)
definition for it.

Bug: v8:12266
Change-Id: I355ca82a9d6b7bc8cd16768a8df93e40f8bfc638
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3199856Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77313}