Reasoning behind "context"

[majido]

dictionary EventDelegationOptions {
  any context;
};

The proposed API proposed a context member that can be used when delegating an event target to a worker. It mentions that it is there to help send additional parameters for the target. We should add an example that shows how this is useful.

Also we should clarify that "context" needs to be structured cloneable otherwise we cannot send it to the worker/worklet.