[ServiceWorker] Update algorithm: propagation of uncaught runtime script error needs to be better specified. (#740)

The uncaught error lives in a different realm/world/JSRuntime/whatever you want to call it from the promise that is supposed to be rejected.  Thus it's non-obvious what it actually means to reject a promise with the uncaught error.

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Reply to this email directly or view it on GitHub:
https://github.com/slightlyoff/ServiceWorker/issues/740