Editorial: Create the realm execution context slightly later

That is, in InitializeHostDefinedRealm,
take the steps that create + push the realm execution context,
and move them to after the realm's fields have been finalized.

Author: jmdyck

spec.html

@@ -11789,11 +11789,6 @@ <h1>InitializeHostDefinedRealm ( ): either a normal completion containing ~unuse
         1. Set _realm_.[[GlobalObject]] to *undefined*.
         1. Set _realm_.[[GlobalEnv]] to *undefined*.
         1. Set _realm_.[[TemplateMap]] to a new empty List.
-        1. Let _newContext_ be a new execution context.
-        1. Set the Function of _newContext_ to *null*.
-        1. Set the Realm of _newContext_ to _realm_.
-        1. Set the ScriptOrModule of _newContext_ to *null*.
-        1. Push _newContext_ onto the execution context stack; _newContext_ is now the running execution context.
         1. If the host requires use of an exotic object to serve as _realm_'s global object, then
           1. Let _global_ be such an object created in a host-defined manner.
         1. Else,
@@ -11804,6 +11799,11 @@ <h1>InitializeHostDefinedRealm ( ): either a normal completion containing ~unuse
           1. Let _thisValue_ be _global_.
         1. Set _realm_.[[GlobalObject]] to _global_.
         1. Set _realm_.[[GlobalEnv]] to NewGlobalEnvironment(_global_, _thisValue_).
+        1. Let _newContext_ be a new execution context.
+        1. Set the Function of _newContext_ to *null*.
+        1. Set the Realm of _newContext_ to _realm_.
+        1. Set the ScriptOrModule of _newContext_ to *null*.
+        1. Push _newContext_ onto the execution context stack; _newContext_ is now the running execution context.
         1. Perform ? SetDefaultGlobalBindings(_realm_).
         1. Create any host-defined global object properties on _global_.
         1. Return ~unused~.