Introduce a generic object serializer/deserializer for WebWorker transfers

[jfirebaugh]

See sketch here.

The idea is to replace all our manually-defined serialize methods with a generic serializer function that recursively serializes the own-properties of an object and records the constructor name, and all our manually-defined deserialize methods with a generic deserializer that looks up the constructor name in a class registry, then uses Object.create to reconstitute an instance without triggering the constructor.

Properties that should not be serialized (e.g. cached computed values) shall be marked as non-enumerable.

In the sketch above, Tranferables that should be transferred can be flagged by setting a transfer: true property on the Transferable. But I think it would be better to make serialize a transfer-only operation, and require you to copy ahead of time of any Transferables you need to copy.

[anandthakker]

Properties that should not be serialized (e.g. cached computed values) shall be marked as non-enumerable.

This is elegant from the point of view of the serialize/deserialize code, but I think the verbosity it requires in client code is a bit much:

(Object.defineProperty: any)(this,  '_cached', {
  writable: true,
  enumerable: false,
  value: this.n * this.n
});

Since classes have to be registered anyway, an alternative would be to allow an optional { include: [property name] } argument to register().

[anandthakker]

I suppose we could also reduce verbosity with a helper function addTemporaryProperty(this, '_cached', this.n * this.n), but that still feels more complicated / less readable to me.

[jfirebaugh]

I'm 👍 on a register option with reversed sense: { omit: [...] }.