Add <link rel=serviceworker>+associated attributes

[sideshowbarker]

This change defines the <link rel=serviceworker> link type and its
associated scope, workertype, and usecache content attributes, as
well as adding the corresponding scope, workerType, and useCache
IDL attributes to the HTMLLinkElement interface definition.

[domenic]

Great stuff. I pushed a couple fixup commits; let me know what you think. Notably I changed workertype to be an enumerated attribute since that matches other similar attributes. That means we would update the service worker spec to refer to the states instead of the attribute value directly, which should be reasonably easy.

/cc @jungkees

[sideshowbarker]

Great stuff. I pushed a couple fixup commits; let me know what you think.

All looks great to me—thanks much

Notably I changed workertype to be an enumerated attribute since that matches other similar attributes.

Thanks, yeah I had not been sure what was best to do there given that we I couldn’t see how we could put state definitions for for the corresponding states just in the HTML spec

That means we would update the service worker spec to refer to the states instead of the attribute value directly, which should be reasonably easy.

OK yes I’ll try to put together a Service Worker PR for that myself (unless @jungkees or somebody else gets to it first)