Attempt standard-compliant worker install & activation

[jakearchibald]

Some of this isn't well specced yet:

https://github.com/slightlyoff/ServiceWorker/issues/144 https://github.com/slightlyoff/ServiceWorker/issues/143

…but I'd like to try and get the "wait for all windows using v1 to go before activating v2" working.

[jakearchibald]

As part of this I'd like to move the registration/install/activation code into WorkerRegistry and WorkerRegistration.

registry register():

• Abort if worker url and glob are already registered
• Abort if worker url is on different origin to page url
• Abort if glob url is on different origin to page url
• If glob already registered, update
• else create & add registration (glob+url)
• Call update

registration update():

• Fetch worker from url
• If network fail, abort silently (offline case)
• If off-domain redirect, abort silently (captive portal)
• If same-domain redirect ???
• If 404 ???
• If != 200 abort silently
• If byte content is identical to active worker, abort
• Eval new worker
• If error thrown ???
• Call oninstall
• Worker is now installing worker
• If error thrown ???
• If waitUntil called, wait on promise
  • If promise rejects ???
• Mark worker as "installed"

Tab load and unload:

• If tab does not match registered glob, abort
• If other tab matches registered glob, abort
• If no installing worker, abort
• If installing worker hasn't finished installing, abort
• Installing worker becomes active worker
• Call onactivate
• If error thrown ??
• If waitUntil called, wait on promise
  • If promise rejects ???
• Mark worker as "activated"

On fetch:

• If page url does not match glob, request normally
• If no active worker, request normally
• If worker not activated, wait on promise
  • If promise rejects ???
• call onfetch
• If forwardTo called, do redirect
• If respondWith called, wait for promise, use response, network failure on rejection