Normative: Allow resetting a Module Namespace object's prototype to n…

…ull (#748)

spec.html

@@ -7999,27 +7999,28 @@ <h1>Module Namespace Exotic Objects</h1>
               A List containing the String values of the exported names exposed as own properties of this object. The list is ordered as if an Array of those String values had been sorted using `Array.prototype.sort` using SortCompare as _comparefn_.
             </td>
           </tr>
+          <tr>
+            <td>
+              [[Prototype]]
+            </td>
+            <td>
+              Null
+            </td>
+            <td>
+              This slot always contains the value *null* (see <emu-xref href="#sec-module-namespace-exotic-objects-setprototypeof-v"></emu-xref>).
+            </td>
+          </tr>
           </tbody>
         </table>
       </emu-table>
-      <p>Module namespace exotic objects provide alternative definitions for all of the internal methods.</p>
-
-      <!-- es6num="9.4.6.1" -->
-      <emu-clause id="sec-module-namespace-exotic-objects-getprototypeof">
-        <h1>[[GetPrototypeOf]] ( )</h1>
-        <p>When the [[GetPrototypeOf]] internal method of a module namespace exotic object _O_ is called, the following steps are taken:</p>
-        <emu-alg>
-          1. Return *null*.
-        </emu-alg>
-      </emu-clause>
+      <p>Module namespace exotic objects provide alternative definitions for all of the internal methods except [[GetPrototypeOf]], which behaves as defined in <emu-xref href="#sec-ordinary-object-internal-methods-and-internal-slots-getprototypeof"></emu-xref>.</p>
 
       <!-- es6num="9.4.6.2" -->
       <emu-clause id="sec-module-namespace-exotic-objects-setprototypeof-v">
         <h1>[[SetPrototypeOf]] ( _V_ )</h1>
         <p>When the [[SetPrototypeOf]] internal method of a module namespace exotic object _O_ is called with argument _V_, the following steps are taken:</p>
         <emu-alg>
-          1. Assert: Either Type(_V_) is Object or Type(_V_) is Null.
-          1. Return *false*.
+          1. Return ? SetImmutablePrototype(_O_, _V_).
         </emu-alg>
       </emu-clause>