Before this we had 3 super related lexical bindings that got injected
into method bodies: .home_object, .this_function,  and new.target.
With this change we get rid of the .home_object one in favor of using
.this_function[home_object_symbol] which allows some simplifications
throughout the code base.

BUG=v8:3768
LOG=N
R=adamk@chromium.org, wingo@igalia.com

Review URL: https://codereview.chromium.org/1154103005

Cr-Commit-Position: refs/heads/master@{#28802}