Hotfix/s33 script errors

This was the bug that made @bmomberger-reciprocity made the breaking change in `cacheable.js`. I tired making doing this._data.owners = new can.List(this._data.owners); but I was still getting a script error mentioned in the comment above the code.

Pressed for time (I was trying to unblock Kostya asap) I came up with this 'solution'.