Adding self.serviceWorker to service workers. (#1426)

* Adding self.serviceWorker to service workers.

* Exposing parsed state

Author: jakearchibald

docs/index.bs

@@ -329,6 +329,7 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
       ServiceWorker includes AbstractWorker;
 
       enum ServiceWorkerState {
+        "parsed",
         "installing",
         "installed",
         "activating",
@@ -926,6 +927,7 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
       interface ServiceWorkerGlobalScope : WorkerGlobalScope {
         [SameObject] readonly attribute Clients clients;
         [SameObject] readonly attribute ServiceWorkerRegistration registration;
+        [SameObject] readonly attribute ServiceWorker serviceWorker;
 
         [NewObject] Promise<void> skipWaiting();
 
@@ -954,6 +956,12 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
       The <dfn attribute for="ServiceWorkerGlobalScope"><code>registration</code></dfn> attribute *must* return the {{ServiceWorkerRegistration}} object that represents the [=ServiceWorkerGlobalScope/service worker=]'s <a>containing service worker registration</a>.
     </section>
 
+    <section>
+      <h4 id="service-worker-global-scope-serviceworker">{{ServiceWorkerGlobalScope/serviceWorker}}</h4>
+
+      The <dfn attribute for="ServiceWorkerGlobalScope"><code>serviceWorker</code></dfn> attribute *must* return the result of [=getting the service worker object=] that represents the [=context object=]'s [=ServiceWorkerGlobalScope/service worker=] in the [=context object=]'s [=relevant settings object=].
+    </section>
+
     <section algorithm="service-worker-global-scope-skipwaiting">
       <h4 id="service-worker-global-scope-skipwaiting">{{ServiceWorkerGlobalScope/skipWaiting()}}</h4>
 
@@ -3158,6 +3166,10 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
       : Output
       :: None
 
+      1. Assert: |state| is not "`parsed`".
+
+          Note: "`parsed`" is the initial state. A [=/service worker=] is never updated to this state.
+
       1. Set |worker|'s [=service worker/state=] to |state|.
       1. Let |settingsObjects| be all [=environment settings objects=] whose [=environment settings object/origin=] is |worker|'s [=service worker/script url=]'s [=url/origin=].
       1. For each |settingsObject| of |settingsObjects|, [=queue a task=] on |settingsObject|'s [=responsible event loop=] in the [=DOM manipulation task source=] to run the following steps: