LibJS: Remove implicit wrapping/unwrapping of completion records

This is an editorial change in the ECMA-262 spec, with similar changes
in some proposals.

See:
- 7575f74
- df899eb
- 9eb5a12
- c81f527

Userland/Libraries/LibJS/Interpreter.h

@@ -90,7 +90,7 @@ public:
         // 11. Create any host-defined global object properties on globalObj.
         static_cast<GlobalObjectType*>(global_object)->initialize_global_object();
 
-        // 12. Return NormalCompletion(empty).
+        // 12. Return unused.
         return interpreter;
     }