Opt cache.add/addAll and importScripts out of a local service worker (#1025)

* Opt cache.add/addAll and importScripts out of a local service worker

* Updating to enum

* Adding to v1

* “service-workers mode”

* Fixing preload request. Generating html.

Author: jakearchibald

docs/index.bs

@@ -1975,6 +1975,7 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
             1. If |r|'s [=request/url=]'s [=url/scheme=] is not one of "<code>http</code>" and "<code>https</code>", then:
                 1. [=fetch/Terminate=] all the ongoing <a>fetches</a> initiated by |requests| with reason *fatal*.
                 1. Break the loop.
+            1. If |r|'s [=request/client=]'s [=environment settings object/global object=] is a {{ServiceWorkerGlobalScope}} object, set |request|'s [=service-workers mode=] to "`foreign`".
             1. Set |r|'s [=request/initiator=] to "<code>fetch</code>" and [=request/destination=] to "<code>subresource</code>".
             1. Add a {{Request}} object associated with |r| to |requestArray|.
             1. Let |responsePromise| be a new <a>promise</a>.
@@ -2265,6 +2266,7 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
         1. Let |serviceWorker| be |request|'s [=request/client=]'s [=environment settings object/global object=]'s [=ServiceWorkerGlobalScope/service worker=].
         1. If |serviceWorker|'s <a>imported scripts updated flag</a> is unset, then:
             1. Let |registration| be |serviceWorker|'s [=containing service worker registration=].
+            1. Set |request|'s [=service-workers mode=] to "`foreign`".
             1. Set |request|'s [=request/cache mode=] to "<code>no-cache</code>" if any of the following are true:
                 * |registration|'s [=service worker registration/use cache=] is false.
                 * The [=current global object=]'s [=force bypass cache for importscripts flag=] is set.
@@ -2588,14 +2590,18 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
 
           To [=fetching scripts/perform the fetch=] given |request|, run the following steps:
 
+          1. Append \`<code>Service-Worker</code>\`/\`<code>script</code>\` to |request|'s [=request/header list=].
+
+            Note: See the definition of the Service-Worker header in Appendix B: Extended HTTP headers.
+
           1. Set |request|'s [=request/cache mode=] to "<code>no-cache</code>" if any of the following are true:
               * |registration|'s [=service worker registration/use cache=] is false.
               * |job|'s [=force bypass cache flag=] is set.
               * |newestWorker| is not null, and |registration|'s [=last update check time=] is not null and the time difference in seconds calculated by the current time minus |registration|’s [=last update check time=] is greater than 86400.
 
               Note: Even if the cache mode is not set to "<code>no-cache</code>", the user agent obeys Cache-Control header's max-age value in the network layer to determine if it should bypass the browser cache.
 
-          1. Set |request|'s [=skip-service-worker flag=].
+          1. Set |request|'s [=service-workers mode=] to "`none`".
           1. If the [=fetching scripts/is top-level=] flag is unset, then return the result of [=/fetching=] |request|.
           1. Append \`<code>Service-Worker</code>\`/\`<code>script</code>\` to |request|'s [=request/header list=].
 
@@ -2909,7 +2915,7 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
               1. Let |preloadRequestHeaders| be |preloadRequest|'s [=request/header list=].
               1. Let |preloadResponseObject| be a new {{Response}} object associated with a new {{Headers}} object whose [=guard=] is "`immutable`".
               1. [=header list/Append=] to |preloadRequestHeaders| a new [=header=] whose [=header/name=] is \`<code>Service-Worker-Navigation-Preload</code>\` and [=header/value=] is |registration|'s [=navigation preload header value=].
-              1. Set |preloadRequest|'s [=skip-service-worker flag=].
+              1. Set |preloadRequest|'s [=service-workers mode=] to "`none`".
               1. Run the following substeps [=in parallel=]:
                   1. [=Fetch=] |preloadRequest|.