serviceWorker postMessage API

[tgvashworth]

Proposed implementation:

• [x] Inject navigator.serviceWorker via devtools extension
• [x] Add postMessage
• [x] Send these requests via websocket to the serviceworker server
• [x] Add postMessage to ServiceWorker class, again using WebSocket

Issues:

• How does the ServiceWorker postMessage get its hands on the active websocket?

[tgvashworth]

Reopened becuase I forgot to do the serviceWorker -> page step.