ServiceWorker

b67c4450 - Rewrite the definition of service worker client and its references

Rewrite the definition of service worker client and its references This changes the definition of the service worker client from type of an environment or an environment settings object to just an environment. As an environment settings object *is-a* environment, this rewrites the references to those objects without using the explicit *type of* language. Instead, this changes to use if-else statments that check types from most-specialized to most-general order. Fixes #1045 #1046