Define how undefined is distinguishable, and remove text that handled…

… undefined specially. Fixes whatwg#962.

index.bs

@@ -3608,6 +3608,7 @@ the following algorithm returns <i>true</i>.
         <thead>
             <tr>
                 <th class="corner"></th>
+                <th><div><span>undefined</span></div>
                 <th><div><span>boolean</span></div>
                 <th><div><span>numeric types</span></div>
                 <th><div><span>bigint</span></div>
@@ -3619,8 +3620,22 @@ the following algorithm returns <i>true</i>.
                 <th><div><span>dictionary-like</span></div>
                 <th><div><span>sequence-like</span></div>
         </thead>
+        <tr>
+            <th>undefined
+            <td>
+            <td>●
+            <td>●
+            <td>●
+            <td>●
+            <td>●
+            <td>●
+            <td>●
+            <td>●
+            <td>●
+            <td>●
         <tr>
             <th>boolean
+            <td class="belowdiagonal">
             <td>
             <td>●
             <td>●
@@ -3634,6 +3649,7 @@ the following algorithm returns <i>true</i>.
         <tr>
             <th>numeric types
             <td class="belowdiagonal">
+            <td class="belowdiagonal">
             <td>
             <td>
             <td>●
@@ -3647,6 +3663,7 @@ the following algorithm returns <i>true</i>.
             <th>bigint
             <td class="belowdiagonal">
             <td class="belowdiagonal">
+            <td class="belowdiagonal">
             <td>(b)
             <td>●
             <td>●
@@ -3660,6 +3677,7 @@ the following algorithm returns <i>true</i>.
             <td class="belowdiagonal">
             <td class="belowdiagonal">
             <td class="belowdiagonal">
+            <td class="belowdiagonal">
             <td>
             <td>●
             <td>●
@@ -3673,6 +3691,7 @@ the following algorithm returns <i>true</i>.
             <td class="belowdiagonal">
             <td class="belowdiagonal">
             <td class="belowdiagonal">
+            <td class="belowdiagonal">
             <td>
             <td>●
             <td>
@@ -3686,6 +3705,7 @@ the following algorithm returns <i>true</i>.
             <td class="belowdiagonal">
             <td class="belowdiagonal">
             <td class="belowdiagonal">
+            <td class="belowdiagonal">
             <td>
             <td>●
             <td>●
@@ -3699,6 +3719,7 @@ the following algorithm returns <i>true</i>.
             <td class="belowdiagonal">
             <td class="belowdiagonal">
             <td class="belowdiagonal">
+            <td class="belowdiagonal">
             <td>(a)
             <td>●
             <td>●
@@ -3712,6 +3733,7 @@ the following algorithm returns <i>true</i>.
             <td class="belowdiagonal">
             <td class="belowdiagonal">
             <td class="belowdiagonal">
+            <td class="belowdiagonal">
             <td>
             <td>
             <td>●
@@ -3725,6 +3747,7 @@ the following algorithm returns <i>true</i>.
             <td class="belowdiagonal">
             <td class="belowdiagonal">
             <td class="belowdiagonal">
+            <td class="belowdiagonal">
             <td>
             <td>●
         <tr>
@@ -3738,6 +3761,7 @@ the following algorithm returns <i>true</i>.
             <td class="belowdiagonal">
             <td class="belowdiagonal">
             <td class="belowdiagonal">
+            <td class="belowdiagonal">
             <td>
     </table>
 
@@ -7348,8 +7372,7 @@ ECMAScript value type.
     to an IDL {{any}} value by running the following algorithm:
 
     1.  If |V| is <emu-val>undefined</emu-val>, then
-        return an {{object}} reference to a special object that represents
-        the ECMAScript <emu-val>undefined</emu-val> value.
+        return the unique {{undefined}} IDL value.
     1.  If |V| is <emu-val>null</emu-val>, then
         return the <emu-val>null</emu-val> {{object|object?}} reference.
     1.  If <a abstract-op>Type</a>(|V|) is Boolean, then
@@ -7371,15 +7394,10 @@ ECMAScript value type.
 </div>
 
 <p id="any-to-es">
-    An IDL {{any}} value is
-    [=converted to an ECMAScript value=]
-    as follows.  If the value is an {{object}}
-    reference to a special object that represents an ECMAScript <emu-val>undefined</emu-val>
-    value, then it is converted to the ECMAScript
-    <emu-val>undefined</emu-val> value.  Otherwise,
-    the rules for converting the [=specific type=]
-    of the IDL {{any}} value
-    as described in the remainder of this section are performed.
+    An IDL {{any}} value is [=converted to an ECMAScript value=]
+    according to the rules for converting
+    the [=specific type=] of the IDL {{any}} value
+    as described in the remainder of this section.
 </p>
 
 
@@ -8884,11 +8902,7 @@ that correspond to the union’s [=member types=].
 <p id="union-to-es">
     An IDL union type value is
     [=converted to an ECMAScript value=]
-    as follows.  If the value is an {{object}}
-    reference to a special object that represents an ECMAScript <emu-val>undefined</emu-val>
-    value, then it is converted to the ECMAScript
-    <emu-val>undefined</emu-val> value.  Otherwise,
-    the rules for converting the [=specific type=]
+    according to the rules for converting the [=specific type=]
     of the IDL union type value as described in this section ([[#es-type-mapping]]).
 </p>