Fix: race-network-and-fetch-handler now uses actual |raceResponse| (#1777)

This commit originates from the work proposed by @monica-ch and accepted a code change suggested
by @domenic, but has been extensively reworked based on review feedback.

This commit corrects response handling for race-network-and-fetch-handler.
Primary Fix: The handler now correctly uses the actual fetch response for |raceResponse| instead of a generic 
                     [=network error=].
Minor Improvement: |timingInfo| is now included in the [=network error=], when returned by
                                   [=Create Fetch Event and Dispatch=], which simplifies the calling code.

Author: yoshisatoyanagisawa

docs/index.bs

@@ -3265,11 +3265,10 @@ spec: storage; urlPrefix: https://storage.spec.whatwg.org/
                   1. Let |raceResponse| be a [=race response=] whose [=race response/value=] is "<code>pending</code>".
                   1. Run the following substeps [=in parallel=], but [=abort when=] |fetchController|'s [=fetch controller/state=] is "<code>terminated</code>" or "<code>aborted</code>":
                       1. Set |raceFetchController| to the result of calling [=fetch=] given |request|, with [=fetch/processResponse=] set to the following steps given a [=/response=] |raceNetworkRequestResponse|:
+                          1. Set |raceResponse|'s [=race response/value=] to |raceNetworkRequestResponse|.
                           1. If |raceNetworkRequestResponse|'s [=response/status=] is [=ok status=], then:
-                              1. Set |raceResponse|'s [=race response/value=] to |raceNetworkRequestResponse|.
                               1. Let |raceNetworkResult| be a [=race result=] whose [=race result/routed response=] is |raceNetworkRequestResponse| and [=race result/used route=] is {{RouterSourceEnum/"network"}}.
                               1. [=queue/Enqueue=] |raceNetworkResult| to |queue|.
-                          1. Otherwise, set |raceResponse|'s [=race response/value=] to a [=network error=].
                   1. [=If aborted=] and |raceFetchController| is not null, then:
                       1. [=fetch controller/Abort=] |raceFetchController|.
                       1. Set |raceResponse| to a [=race response=] whose [=race response/value=] is null.
@@ -3282,6 +3281,8 @@ spec: storage; urlPrefix: https://storage.spec.whatwg.org/
                   1. Wait until |queue| is not empty.
                   1. Let |result| be the result of [=dequeue=] |queue|.
                   1. Let |routedResponse| be |result|'s [=race result/routed response=].
+                  1. If |routedResponse| is null:
+                      1. Return |timingInfo|.
                   1. If |result|'s [=race result/used route=] is {{RouterSourceEnum/"network"}}, then:
                       1. Set |routedResponse|'s [=service worker timing info=] be set to |timingInfo|.
                   1. Set |routedResponse|'s [=service worker timing info=]'s [=service worker timing info/worker final router source=] be set to |result|'s [=race result/used route=].
@@ -3340,6 +3341,9 @@ spec: storage; urlPrefix: https://storage.spec.whatwg.org/
       1. Let |eventHandled| be null.
       1. Let |handleFetchFailed| be false.
       1. Let |respondWithEntered| be false.
+      1. Let |networkError| be a [=network error=].
+      1. If |raceResponse| is not null:
+          1. Set |networkError|'s [=response/service worker timing info=] to |timingInfo|.
       1. Let |shouldSoftUpdate| be true if any of the following are true, and false otherwise:
           * |request| is a [=non-subresource request=].
           * |request| is a [=subresource request=] and |registration| is [=stale=].
@@ -3399,15 +3403,15 @@ spec: storage; urlPrefix: https://storage.spec.whatwg.org/
       1. If |respondWithEntered| is false, then:
           1. If |eventCanceled| is true, then:
               1. If |eventHandled| is not null, then [=reject=] |eventHandled| with a "{{NetworkError}}" {{DOMException}} in |workerRealm|.
-              2. Return a [=network error=].
+              2. Return |networkError|.
           1. If |eventHandled| is not null, then [=resolve=] |eventHandled|.
-          1. If |raceResponse|'s [=race response/value=] is not null, then:
+          1. If |raceResponse| is not null, and |raceResponse|'s [=race response/value=] is not null, then:
               1. Wait until |raceResponse|'s [=race response/value=] is not "<code>pending</code>".
               1. If |raceResponse|'s [=race response/value=] is a [=/response=], return |raceResponse|'s [=race response/value=].
           1. Return null.
       1. If |handleFetchFailed| is true, then:
           1. If |eventHandled| is not null, then [=reject=] |eventHandled| with a "{{NetworkError}}" {{DOMException}} in |workerRealm|.
-          2. Return a [=network error=].
+          2. Return |networkError|.
       1. If |eventHandled| is not null, then [=resolve=] |eventHandled|.
       1. Return |response|.
   </section>