Check for transferable detachedness after serializing

Since serializing can make a transferable detached, it seems better to throw for that later.

See https://bugs.chromium.org/p/chromium/issues/detail?id=816447 for more context.

Tests: web-platform-tests/wpt#9672.

Author: annevk

source

@@ -8808,13 +8808,8 @@ o.myself = o;</pre>
      <span>[[Detached]]</span> internal slot, then throw a
      <span>"<code>DataCloneError</code>"</span> <code>DOMException</code>.</p></li>
 
-     <li><p>If <var>transferable</var> has an [[ArrayBufferData]] internal slot and either !
-     <span>IsSharedArrayBuffer</span>(<var>transferable</var>) is true or !
-     <span>IsDetachedBuffer</span>(<var>transferable</var>) is true, then throw a
-     <span>"<code>DataCloneError</code>"</span> <code>DOMException</code>.</p></li>
-
-     <li><p>If <var>transferable</var> has a <span>[[Detached]]</span> internal slot and
-     <var>transferable</var>.<span>[[Detached]]</span> is true, then throw a
+     <li><p>If <var>transferable</var> has an [[ArrayBufferData]] internal slot and !
+     <span>IsSharedArrayBuffer</span>(<var>transferable</var>) is true, then throw a
      <span>"<code>DataCloneError</code>"</span> <code>DOMException</code>.</p></li>
 
      <li><p>If <var>memory</var>[<var>transferable</var>] <span data-x="map exists">exists</span>,
@@ -8841,6 +8836,14 @@ o.myself = o;</pre>
     <var>transferList</var>:</p>
 
     <ol>
+     <li><p>If <var>transferable</var> has an [[ArrayBufferData]] internal slot and !
+     <span>IsDetachedBuffer</span>(<var>transferable</var>) is true, then throw a
+     <span>"<code>DataCloneError</code>"</span> <code>DOMException</code>.</p></li>
+
+     <li><p>If <var>transferable</var> has a <span>[[Detached]]</span> internal slot and
+     <var>transferable</var>.<span>[[Detached]]</span> is true, then throw a
+     <span>"<code>DataCloneError</code>"</span> <code>DOMException</code>.</p></li>
+
      <li><p>Let <var>dataHolder</var> be <var>memory</var>[<var>transferable</var>].</p></li>
 
      <li>
@@ -121000,6 +121003,7 @@ INSERT INTERFACES HERE
   Jeremey Hustman,
   Jeremy Keith,
   Jeremy Orlow,
+  Jeremy Roman,
   Jeroen van der Meer,
   Jerry Smith,
   Jesse Ren&eacute;e Beach,