Since our shape guards are kind of broken now (on purpose, waiting for ObjShrink), we need this to run (a modified version of) bitwise-and.
Created attachment 576895 [details] [diff] [review] Patch We can probably get rid of some TypeOracle methods. I'll get to it after getelem/setelem lands to avoid updating the patch David is reviewing.
Created attachment 576897 [details] [diff] [review] Patch Clarify the abort message a bit. According to the isOwnProperty comment we don't abort for properties that are non-writable etc on creation.