This patch uses a bit in the Variable bit fields to distinguish
static private names from instance private names, so that we
can check the conflicts of private accessors that are complementary
but with different staticness in the parser, and use this
information later when generating code for checking static brands
for private method access.

Design doc: https://docs.google.com/document/d/1rgGRw5RdzaRrM-GrIMhsn-DLULtADV2dmIdh_iIZxlc/edit

Bug: v8:8330
Change-Id: I8d70600e594e3d07f77ea519751b7ca2e0de87b5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1781010Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Joyee Cheung <joyee@igalia.com>
Cr-Commit-Position: refs/heads/master@{#63677}