Expressions in class heritage position do not have access to the
inheriting class's private names, only its lexical bindings. The parser
currently uses the same scope chain for both.

This CL makes scopes in class heritage position skip their outer class
when resolving private names. Whether a scope needs to skip is kept as a
bit on various scope-related data structures.

See implementation doc at
https://docs.google.com/document/d/1d3o_SQqcICxfjLMw53OOaiIQux0ppNHQJnjZHtCQLwA

Bug: v8:9177
Change-Id: I77e491a9d4a261131274f12ddf052af7ac31a921
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1769486
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63586}