Editorial: Consistify re Agent Events Record in/of <List>

PR tc39#2947 changed 6 occurrences of:
`the element of _execution_.[[EventsRecords]] whose ...`
to:
`the Agent Events Record of _execution_.[[EventsRecords]] whose ...`

But there were also 2 pre-existing occurrences of
`the Agent Events Record in _execution_.[[EventsRecords]] whose ...`
with "in" rather than "of", in {Enter,Leave}CriticalSection.

To achieve consistency, this commit changes the latter (with "in")
to match the former (with "of").
Roughly speaking, this conforms to PR tc39#2941.

spec.html

@@ -42098,7 +42098,7 @@ <h1>
           1. If _WL_ has a Synchronize event, then
             1. NOTE: A _WL_ whose critical section has been entered at least once has a Synchronize event set by LeaveCriticalSection.
             1. Let _execution_ be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
-            1. Let _eventsRecord_ be the Agent Events Record in _execution_.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
+            1. Let _eventsRecord_ be the Agent Events Record of _execution_.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
             1. Let _enterEvent_ be a new Synchronize event.
             1. Append _enterEvent_ to _eventsRecord_.[[EventList]].
             1. Let _leaveEvent_ be the Synchronize event in _WL_.
@@ -42119,7 +42119,7 @@ <h1>
         <emu-alg>
           1. Assert: The surrounding agent is in the critical section for _WL_.
           1. Let _execution_ be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
-          1. Let _eventsRecord_ be the Agent Events Record in _execution_.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
+          1. Let _eventsRecord_ be the Agent Events Record of _execution_.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
           1. Let _leaveEvent_ be a new Synchronize event.
           1. Append _leaveEvent_ to _eventsRecord_.[[EventList]].
           1. Set the Synchronize event in _WL_ to _leaveEvent_.