Editorial: add assertion in MakeSuperPropertyReference

spec.html

@@ -10186,7 +10186,7 @@ <h1>The Environment Record Type Hierarchy</h1>
               HasSuperBinding()
             </td>
             <td>
-              Determine if an Environment Record establishes a `super` method binding. Return *true* if it does and *false* if it does not.
+              Determine if an Environment Record establishes a `super` method binding. Return *true* if it does and *false* if it does not. If it returns *true* it implies that the Environment Record is a Function Environment Record, although the reverse implication does not hold.
             </td>
           </tr>
           <tr>
@@ -19408,6 +19408,7 @@ <h1>Runtime Semantics: Evaluation</h1>
           1. If IsConstructor(_func_) is *false*, throw a *TypeError* exception.
           1. Let _result_ be ? Construct(_func_, _argList_, _newTarget_).
           1. Let _thisER_ be GetThisEnvironment().
+          1. Assert: _thisER_ is a Function Environment Record.
           1. Perform ? BindThisValue(_thisER_, _result_).
           1. Let _F_ be _thisER_.[[FunctionObject]].
           1. Assert: _F_ is an ECMAScript function object.
@@ -19443,6 +19444,7 @@ <h1>
         <emu-alg>
           1. Let _env_ be GetThisEnvironment().
           1. Assert: _env_.HasSuperBinding() is *true*.
+          1. Assert: _env_ is a Function Environment Record.
           1. Let _baseValue_ be GetSuperBase(_env_).
           1. Return the Reference Record { [[Base]]: _baseValue_, [[ReferencedName]]: _propertyKey_, [[Strict]]: _strict_, [[ThisValue]]: _actualThis_ }.
         </emu-alg>