Inline `Set.prototype.has` in CacheIR when called with objects.
Implementing `MacroAssembler::hashObject()` on 32-bit platforms is difficult,
because it uses 64-bit operations, so we either have to allocate twice as much
registers for `Register64` or alternatively spill the values on the stack. For
now just punt and only support this optimisation on 64-bit platforms.
Differential Revision: https://phabricator.services.mozilla.com/D118977
