Handing fetch termination (#1178)

* Handing fetch termination

* Catering for navigation preloads

* Missing dot

Author: jakearchibald

docs/index.bs

@@ -2936,6 +2936,7 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
       1. Let |client| be |request|'s [=request/client=].
       1. Let |reservedClient| be |request|'s [=request/reserved client=].
       1. Let |preloadResponse| be a new [=promise=].
+      1. Let |fetchInstance| be the instance of the [=/fetch=] algorithm representing the ongoing fetch.
       1. Assert: |request|'s [=request/destination=] is not "<code>serviceworker</code>".
       1. If |request| is a <a>potential-navigation-or-subresource request</a>, then:
           1. Return null.
@@ -2961,13 +2962,14 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
               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 [=service-workers mode=] to "`none`".
               1. Run the following substeps [=in parallel=]:
-                  1. [=Fetch=] |preloadRequest|.
+                  1. [=Fetch=] |preloadRequest| and let |preloadFetchInstance| be the instance of the [=/fetch=] algorithm.
 
                       To [=process response=] for |navigationPreloadResponse|, run these substeps:
 
                       1. If |navigationPreloadResponse|'s [=response/type=] is "`error`", reject |preloadResponse| with a `TypeError` and terminate these substeps.
                       1. Associate |preloadResponseObject| with |navigationPreloadResponse|.
                       1. Resolve |preloadResponse| with |navigationPreloadResponse|.
+                  1. If |fetchInstance| is [=fetch/terminated=], then [=fetch/terminate=] |preloadFetchInstance| with the aborted flag set.
           1. Else, resolve |preloadResponse| with undefined.
 
           Note: From this point, the [=/service worker client=] starts to <a>use</a> its <a>active service worker</a>'s <a>containing service worker registration</a>.
@@ -2987,9 +2989,10 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
       1. Invoke <a>Run Service Worker</a> algorithm with |activeWorker| as the argument.
       1. <a>Queue a task</a> |task| to run the following substeps:
           1. Let |e| be the result of <a>creating an event</a> with {{FetchEvent}}.
+          1. Let |requestObject| be a new {{Request}} object associated with |request| and a new associated {{Headers}} object whose [=guard=] is "`immutable`".
           1. Initialize |e|’s {{Event/type}} attribute to {{fetch!!event}}.
           1. Initialize |e|’s {{Event/cancelable}} attribute to true.
-          1. Initialize |e|’s {{FetchEvent/request}} attribute to a new {{Request}} object associated with |request| and a new associated {{Headers}} object whose [=guard=] is "`immutable`".
+          1. Initialize |e|’s {{FetchEvent/request}} attribute to |requestObject|.
           1. Initialize |e|’s {{FetchEvent/preloadResponse}} to |preloadResponse|.
           1. Initialize |e|'s {{FetchEvent/clientId}} attribute to |client|'s [=environment/id=].
           1. If |request| is a <a>non-subresource request</a> and |request|'s [=request/destination=] is not {{RequestDestination/"report"}}, initialize |e|'s {{FetchEvent/reservedClientId}} attribute to |reservedClient|'s [=environment/id=], and to the empty string otherwise.
@@ -3002,6 +3005,7 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
               1. If |e|'s [=FetchEvent/respond-with error flag=] is set, set |handleFetchFailed| to true.
               1. Else, set |response| to |e|'s [=FetchEvent/potential response=].
           1. If |e|'s <a>canceled flag</a> is set, set |eventCanceled| to true.
+          1. If |fetchInstance| is [=fetch/terminated=], then [=queue a task=] to [=AbortSignal/signal abort=] on |requestObject|'s {{Request/signal}}.
 
           If |task| is discarded or the script has been aborted by the <a lt="terminate service worker">termination</a> of |activeWorker|, set |handleFetchFailed| to true.