This patch sets the name slot of the private name symbols for
private fields and display the names in error messages of invalid
private field accesses.

TBR: adamk@chromium.org
Bug: v8:8144
Change-Id: Id34c468e2bddd1c3001517b4d447c7497402df76
Reviewed-on: https://chromium-review.googlesource.com/c/1374332Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Joyee Cheung <joyee@igalia.com>
Cr-Commit-Position: refs/heads/master@{#58601}