1) Computed property keys (esp functions in them) shouldn't be inside
the object literal scope.

2) I was using an imprecise "maybe uses super" and storing it to
preparse data. This won't fly, since it pollutes sister scopes and
leads to confusion wrt whether an object literal needs a home object
or not. Made it precise (mostly cancelling changes in the original CL).

3) PreParser::NewSuperPropertyReference was creating a VariableProxy for
this_function (which made it used) -> inconsistent scopes between
parsing and preparsing.

4) MultipleEntryBlockContextScope was messing up the accumulator

Original: https://chromium-review.googlesource.com/c/v8/v8/+/2563275

This saves memory (the home object doesn't need to be stored for each
method, but only once per class) and hopefully makes the home object
a constant in the optimized code.

Detailed documentation of the changes:
https://docs.google.com/document/d/1ZVXcoQdf9IdMsnRI9iyUjyq9NDoEyx9nA3XqMgwflMs/edit?usp=sharing

Bug: v8:9237, chromium:1167918, chromium:1167981, chromium:1167988, chromium:1168055
Change-Id: I4f53f18cc18762c33e53d8c802909b42f1c33538
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2637220Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72169}