Support SharedArrayBuffer in StructuredCloneWithTransfer

source

@@ -7650,6 +7650,10 @@ interface <dfn>DOMStringMap</dfn> {
   <span>StructuredCloneWithTransfer</span> abstract operation directly. (Technically, by
   <span>IsTransferable</span> and <span>TransferHelper</span>.)</p>
 
+  <p class="note">SharedArrayBuffer objects are unique in that while they are <span>transferable
+  objects</span>, they are not detached as a result of transfering. Therefore they can be
+  transferred and used again. Only SharedArrayBuffer objects are given this capability.</p>
+
   <h4 id="structuredclonewithtransfer"><dfn data-export="">StructuredCloneWithTransfer</dfn> (
   <var>input</var>, <var>transferList</var>, <var>targetRealm</var> )</h4>
 
@@ -8008,6 +8012,9 @@ interface <dfn>DOMStringMap</dfn> {
     </ol>
    </li>
 
+   <li><p>Otherwise, if <var>O</var> has a [[SharedArrayBufferData]] internal slot, then return
+   true.</p></li>
+
    <li>
     <p>Otherwise, if <var>O</var> has a [[<span>Detached</span>]] internal slot, then:</p>
 
@@ -8035,12 +8042,19 @@ interface <dfn>DOMStringMap</dfn> {
      [[ArrayBufferData]] internal slot value of <var>input</var>.</p></li>
 
      <li><p>Perform ! <span>DetachArrayBuffer</span>(<var>input</var>).</p></li>
-
-     <li><p>Return <var>output</var>.</p></li>
     </ol>
    </li>
 
-   <li><p>Return ? <var>input</var>.[[<span>Transfer</span>]](<var>targetRealm</var>).</p></li>
+   <li><p>Otherwise, if <var>input</var> has a [[SharedArrayBufferData]] internal slot, then let
+   <var>output</var> be a new SharedArrayBuffer object in <var>targetRealm</var> whose
+   [[SharedArrayBufferByteLength]] internal slot value is the [[SharedArrayBufferByteLength]]
+   internal slot value of <var>input</var>, and whose [[SharedArrayBufferData]] internal slot value
+   is the [[SharedArrayBufferData]] internal slot value of <var>input</var>.</p></li>
+
+   <li><p>Otherwise, let <var>output</var> be ?
+   <var>input</var>.[[<span>Transfer</span>]](<var>targetRealm</var>).</p></li>
+
+   <li><p>Return <var>output</var>.</p></li>
   </ol>
 
   <h4>Monkey patch for <code>Blob</code> and <code>FileList</code> objects</h4>
@@ -117018,6 +117032,7 @@ INSERT INTERFACES HERE
 
    <dt id="refsJAVASCRIPT">[JAVASCRIPT]</dt>
    <dd><cite><a href="https://tc39.github.io/ecma262/">ECMAScript Language Specification</a></cite>. Ecma International.</dd>
+   <dd><cite><a href="https://tc39.github.io/ecmascript_sharedmem/shmem.html">ECMAScript Shared Memory and Atomics</a></cite>. Ecma International.</dd>
    <dd><cite><a href="https://javascript.spec.whatwg.org/">JavaScript Standard</a></cite>, M. Bynens. WHATWG.</dd>
 
    <dt id="refsJLREQ">[JLREQ]</dt>