fix 985 add abort path to createCredential alg (#1005)

index.bs

@@ -994,6 +994,10 @@ a numbered step. If outdented, it (today) is rendered as a bullet in the midst o
         ::  [=set/For each=] |authenticator| in |issuedRequests| invoke the [=authenticatorCancel=] operation on |authenticator|
             and [=set/remove=] |authenticator| from |issuedRequests|.
 
+        :   If the user exercises a user agent user-interface option to cancel the process,
+        ::  [=set/For each=] |authenticator| in |issuedRequests| invoke the [=authenticatorCancel=] operation on |authenticator|
+            and [=set/remove=] |authenticator| from |issuedRequests|. Return a {{DOMException}} whose name is "{{NotAllowedError}}".
+
         :   If the <code>|options|.{{CredentialCreationOptions/signal}}</code> is [=present=] and its
             [=AbortSignal/aborted flag=] is set to [TRUE],
         ::  [=set/For each=] |authenticator| in |issuedRequests| invoke the [=authenticatorCancel=]
@@ -1332,7 +1336,7 @@ When this method is invoked, the user agent MUST execute the following algorithm
         ::  [=set/For each=] |authenticator| in |issuedRequests| invoke the [=authenticatorCancel=] operation on
             |authenticator| and [=set/remove=] |authenticator| from |issuedRequests|.
 
-        :   If the user exercises a user-interface option to cancel the process,
+        :   If the user exercises a user agent user-interface option to cancel the process,
         ::  [=set/For each=] |authenticator| in |issuedRequests| invoke the [=authenticatorCancel=] operation on |authenticator|
             and [=set/remove=] |authenticator| from |issuedRequests|. Return a {{DOMException}} whose name is "{{NotAllowedError}}".