Port 55643564

Original Commit Message:

    This removes a shortcut to a "CEntryStub" from the instance object and
    instead loads those values via the root set which is also referenced
    from the instance. It makes instance objects smaller.

R=mstarzinger@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: I2ad2f3479431dae71f47af7ad5c722e46fd592d6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1716368Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#62897}