Currently v8 ignores class instance fields when determining how many
properties to preallocate for a given function. This cl changes v8's
behavior to start preallocating for instance fields in addition to
properties.

Bug: v8:8774
Change-Id: If598c2ba8a1b14bd0293f36bae7d35e2d85f7898
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1560216
Commit-Queue: Joshua Litt <joshualitt@google.com>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60882}