Adding implementation for step 9 which is missing for spec:
https://tc39.github.io/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-ownpropertykeys
Update bytecode_expectations as well.

Bug v8:6776

Change-Id: Id191f9604e2dc08e71cbcff8ebd5707c233af193
Reviewed-on: https://chromium-review.googlesource.com/c/1419779Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#59180}