Allow promise hydration to work with instances of Promise from another context #17235
Description
Describe the problem
Sort of similar to sveltejs/devalue#5 (wow, 2018), if I try to serialize an object for hydration and it contains instances of Promise from another context - like it would when I'm running code with vm.runInNewContext() - then Svelte fails to see this as a promise, and devalue balks at having to serialize an arbitrary POJO.
Describe the proposed solution
The only thing I can think of is to try duck typing this. How would we feel about result && typeof result.then == 'function' instead of result instanceof Promise?
Importance
nice to have