Fix promise handling; remove extensions allowed flag

This makes waitUntil() wait only the given promises instead of all the
promises in the given promises' chains. So, it removes the direct
references to the promises internal slots.

This replaces the extensions allowed flag with the combinations of the
pending promises count and the state of the event's dispatch flag.

docs/index.bs

@@ -1289,33 +1289,34 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
 
     An {{ExtendableEvent}} object has an associated <dfn for="ExtendableEvent">extend lifetime promises</dfn> (an array of <a>promises</a>). It is initially an empty array.
 
-    An {{ExtendableEvent}} object has an associated <dfn for="ExtendableEvent" id="extensions-allowed-flag">extensions allowed flag</dfn>. It is initially set.
-
     An {{ExtendableEvent}} object has an associated <dfn for="ExtendableEvent">pending promises count</dfn> (the number of pending promises in the [=ExtendableEvent/extend lifetime promises=]). It is initially set to zero.
 
     [=/Service workers=] have two <a>lifecycle events</a>, {{install!!event}} and {{activate!!event}}. [=/Service workers=] use the {{ExtendableEvent}} interface for {{activate!!event}} event and {{install!!event}} event.
 
     <a href="#extensibility">Service worker extensions</a> that <a href="#extension-to-service-worker-global-scope">define event handlers</a> *may* also use or extend the {{ExtendableEvent}} interface.
 
-    Note: To extend the lifetime of a [=/service worker=], algorithms that <a>dispatch</a> events using the {{ExtendableEvent}} interface run [=Extend Service Worker Lifetime=] algorithm after <a>dispatching</a> the event. See <a>Handle Fetch</a>, <a>Handle Foreign Fetch</a>, and <a>Handle Functional Event</a>.
-
     <section algorithm="wait-until-method">
       <h4 id="wait-until-method">{{ExtendableEvent/waitUntil()|event.waitUntil(f)}}</h4>
 
       {{ExtendableEvent/waitUntil()}} method extends the lifetime of the event.
 
       <dfn method for="ExtendableEvent"><code>waitUntil(|f|)</code></dfn> method *must* run these steps:
 
-        1. If the <a>extensions allowed flag</a> is unset, then:
+        1. If the [=ExtendableEvent/pending promises count=] is zero and the [=dispatch flag=] is unset, then:
             1. <a>Throw</a> an "{{InvalidStateError}}" exception.
             1. Abort these steps.
+
+            Note: If no lifetime extension promise has been added in the task that called the event handlers), calling {{ExtendableEvent/waitUntil()}} in subsequent asynchronous tasks will throw.
+
         1. Add |f| to the [=ExtendableEvent/extend lifetime promises=].
         1. Increase the [=ExtendableEvent/pending promises count=] by one.
 
             Note: The [=ExtendableEvent/pending promises count=] is increased even if the given promise has already been settled. The corresponding count decrease is done within [=Handle Extend Lifetime Promise=] algorithm.
 
         1. Run [=Handle Extend Lifetime Promise=] with the [=context object=] and |f|.
         1. Return.
+
+        The user agent *should not* <a lt="terminate service worker">terminate</a> the [=/service worker=] associated with |event|'s <a>relevant settings object</a>'s [=environment settings object/global object=] when |event|'s [=dispatch flag=] is set or |event|'s [=ExtendableEvent/pending promises count=] is not zero. However, the user agent *may* impose a time limit to this lifetime extension.
     </section>
 
     [=/Service workers=] and <a href="#extensibility">extensions</a> that <a href="#extension-to-service-worker-global-scope">define event handlers</a> *may* define their own behaviors, allowing the [=ExtendableEvent/extend lifetime promises=] to suggest operation length, and the rejected state of any of the <a>promise</a> in [=ExtendableEvent/extend lifetime promises=] to suggest operation failure.
@@ -2696,9 +2697,8 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
           1. Let |e| be the result of <a>creating an event</a> with {{InstallEvent}}.
           1. Initialize |e|’s {{Event/type}} attribute to {{install!!event}}.
           1. <a>Dispatch</a> |e| at |installingWorker|'s [=service worker/global object=].
-          1. Invoke [=Extend Service Worker Lifetime=] with |e|.
           1. *WaitForAsynchronousExtensions*: Run the following substeps <a>in parallel</a>:
-              1. Wait until |e|'s <a>extensions allowed flag</a> is unset.
+              1. Wait until |e|'s [=ExtendableEvent/pending promises count=] is zero.
               1. If the result of <a>waiting for all</a> of |e|'s <a>extend lifetime promises</a> rejected, set |installFailed| to true.
 
           If |task| is discarded or the script has been aborted by the <a lt="Terminate Service Worker">termination</a> of |installingWorker|, set |installFailed| to true.
@@ -2762,8 +2762,7 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
           1. Let |e| be the result of <a>creating an event</a> with {{ExtendableEvent}}.
           1. Initialize |e|’s {{Event/type}} attribute to {{activate!!event}}.
           1. <a>Dispatch</a> |e| at |activeWorker|'s [=service worker/global object=].
-          1. Invoke [=Extend Service Worker Lifetime=] with |e|.
-          1. *WaitForAsynchronousExtensions*: Wait, <a>in parallel</a>, until |e|'s <a>extensions allowed flag</a> is unset.
+          1. *WaitForAsynchronousExtensions*: Wait, <a>in parallel</a>, until |e|'s [=ExtendableEvent/pending promises count=] is zero.
       1. Wait for |task| to have executed or been discarded, or the script to have been aborted by the <a lt="terminate service worker">termination</a> of |activeWorker|.
       1. Wait for the step labeled *WaitForAsynchronousExtensions* to complete.
       1. Run the <a>Update Worker State</a> algorithm passing |registration|'s <a>active worker</a> and *activated* as the arguments.
@@ -2847,21 +2846,6 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
       1. Abort the script currently running in |serviceWorker|.
   </section>
 
-  <section algorithm>
-    <h3 id="extend-service-worker-lifetime-algorithm"><dfn>Extend Service Worker Lifetime</dfn></h3>
-
-      : Input
-      :: |event|, an {{ExtendableEvent}} object
-      : Output
-      :: None
-
-      1. If |event|'s [=ExtendableEvent/pending promises count=] is zero, unset |event|'s [=ExtendableEvent/extensions allowed flag=] and abort these steps.
-
-          Note: If no lifetime extension promise has been added up to this point (i.e., at the end of the task that called the event handlers), the [=ExtendableEvent/extensions allowed flag=] is immediately unset. Calling {{ExtendableEvent/waitUntil()}} in subsequent asynchronous tasks will throw.
-
-      The user agent *should not* <a lt="terminate service worker">terminate</a> the [=/service worker=] associated with |event|'s <a>relevant settings object</a>'s [=environment settings object/global object=] until |event|'s <a>extensions allowed flag</a> is unset. However, the user agent *may* impose a time limit to this lifetime extension.
-  </section>
-
   <section algorithm>
     <h3 id="handle-extend-lifetime-promise-algorithm"><dfn>Handle Extend Lifetime Promise</dfn></h3>
 
@@ -2871,14 +2855,8 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
       : Output
       :: None
 
-      1. Wait until |promise| is settled [=in parallel=].
-      2. [=Queue a microtask=] to run the following substeps:
-          1. Decrease |event|'s [=ExtendableEvent/pending promises count=] by one.
-          1. For each |reaction| in |promise|.\[[PromiseFulfillReactions]]:
-              1. Append |reaction|.\[[Capability]].\[[Promise]] to |event|'s [=ExtendableEvent/extend lifetime promises=].
-              1. Increase |event|'s [=ExtendableEvent/pending promises count=] by one.
-              1. Invoke [=Handle Extend Lifetime Promise=] with |event| and |reaction|.\[[Capability]].\[[Promise]].
-          1. If |event|'s [=ExtendableEvent/pending promises count=] is zero, unset |event|'s [=ExtendableEvent/extensions allowed flag=].
+      1. Wait, [=in parallel=], until |promise| is settled and |promise|'s <code>then</code> methods, if any, in the task where |promise| has been settled have executed.
+      2. [=Queue a microtask=], on |promise|'s [=relevant settings object=]'s [=responsible event loop=], to decrease |event|'s [=ExtendableEvent/pending promises count=] by one.
   </section>
 
   <section algorithm>
@@ -2959,7 +2937,6 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
           1. If |request| is a <a>navigation request</a>, initialize |e|'s {{FetchEvent/targetClientId}} attribute to |request|'s [=request/target client id=], and to the empty string otherwise.
           1. Let the {{FetchEvent/isReload}} attribute of |e| be initialized to <code>true</code> if |request|'s [=request/client=] is a <a>window client</a> and the event was dispatched with the user's intention for the page reload, and <code>false</code> otherwise.
           1. <a>Dispatch</a> |e| at |activeWorker|'s [=service worker/global object=].
-          1. Invoke [=Extend Service Worker Lifetime=] with |e|.
           1. If |e|'s [=FetchEvent/respond-with entered flag=] is set, set |respondWithEntered| to true.
           1. If |e|'s [=FetchEvent/wait to respond flag=] is set, then:
               1. Wait until |e|'s [=FetchEvent/wait to respond flag=] is unset.
@@ -3023,7 +3000,6 @@ spec: webappsec-referrer-policy; urlPrefix: https://w3c.github.io/webappsec-refe
           1. Initialize |e|’s {{ForeignFetchEvent/request}} attribute to |r|.
           1. Initialize |e|’s {{ForeignFetchEvent/origin}} attribute to the  <a lt="Unicode serialization of an origin">Unicode serialization</a> of |request|'s [=request/origin=].
           1. <a>Dispatch</a> |e| at |activeWorker|'s [=service worker/global object=].
-          1. Invoke [=Extend Service Worker Lifetime=] with |e|.
           1. If |e|'s [=ForeignFetchEvent/respond-with entered flag=] is set, set |respondWithEntered| to true.
           1. If |e|'s <a>wait to respond flag</a> is set, wait until |e|'s <a>wait to respond flag</a> is unset.
           1. Let |internalResponse| be |e|'s [=ForeignFetchEvent/potential response=].
@@ -3085,7 +3061,6 @@ 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 these substeps:
           1. Invoke |callbackSteps| with |activeWorker|'s [=service worker/global object=] as its argument.
-          1. Invoke [=Extend Service Worker Lifetime=] with |event|.
 
           The |task| *must* use |activeWorker|'s <a>event loop</a> and the <a>handle functional event task source</a>.