pass abortsignal reason to close a subscription

spec.bs

@@ -37,6 +37,7 @@ urlPrefix: https://dom.spec.whatwg.org; spec: DOM
     for: AbortSignal
       text: dependent signals; url: abortsignal-dependent-signals
       text: signal abort; url:abortsignal-signal-abort
+      text: reason; url:abortsignal-abort-reason
 </pre>
 
 <style>
@@ -262,7 +263,8 @@ The <dfn attribute for=Subscriber><code>signal</code></dfn> getter steps are to
 </div>
 
 <div algorithm>
-  To <dfn>close a subscription</dfn> given a {{Subscriber}} |subscriber|, run these steps:
+  To <dfn>close a subscription</dfn> given a {{Subscriber}} |subscriber|, and
+  an optional {{any}} |reason|, run these steps:
 
     1. If |subscriber|'s [=Subscriber/active=] is false, then return.
 
@@ -292,9 +294,10 @@ observable.subscribe({}, {signal: outerController.signal});
 
     1. Set |subscriber|'s [=Subscriber/active=] boolean to false.
 
-    1. [=AbortSignal/Signal abort=] |subscriber|'s [=Subscriber/subscription controller=].
+    1. [=AbortSignal/Signal abort=] |subscriber|'s [=Subscriber/subscription controller=]
+       with |reason|, if it is given.
 
-       Issue: Abort with an appropriate abort reason.
+       Issue: Abort with an appropriate abort reason if none given.
 
     1. [=list/For each=] |teardown| of |subscriber|'s [=Subscriber/teardown callbacks=] sorted in
        reverse insertion order:
@@ -532,7 +535,8 @@ An <dfn>internal observer</dfn> is a [=struct=] with the following [=struct/item
        1. Otherwise, [=AbortSignal/add|add the following abort algorithm=] to |options|'s
           {{SubscribeOptions/signal}}:
 
-          1. [=close a subscription|Close=] |subscriber|.
+          1. [=close a subscription|Close=] |subscriber| with |options|'s
+             {{SubscribeOptions/signal}} [=AbortSignal/reason=]{{reason}}.
 
     1. If [=this=]'s [=Observable/subscribe callback=] is a {{SubscribeCallback}}, [=invoke=] it
        with |subscriber|.