change [[NewTarget]] slot type in Function Environment Records

Author: michaelficarra

spec.html

@@ -10691,7 +10691,7 @@ <h1>Function Environment Records</h1>
                 [[NewTarget]]
               </td>
               <td>
-                an Object or *undefined*
+                a constructor or *undefined*
               </td>
               <td>
                 If this Environment Record was created by the [[Construct]] internal method, [[NewTarget]] is the value of the [[Construct]] _newTarget_ parameter. Otherwise, its value is *undefined*.