diff --git a/source b/source
index 419a2fdbd0e..9aeb9c2618f 100644
--- a/source
+++ b/source
@@ -78044,11 +78044,17 @@ interface <dfn data-export="" data-dfn-type="interface">Window</dfn> : <span>Eve
   void <span data-x="dom-window-cancelAnimationFrame">cancelAnimationFrame</span>(unsigned long handle);
 
   void <span data-x="dom-window-postMessage">postMessage</span>(any message, USVString targetOrigin, optional sequence&lt;<span data-x="idl-object">object</span>&gt; transfer = []);
+  void <span data-x="dom-window-postMessage-options">postMessage</span>(any message, optional <span>WindowPostMessageOptions</span> options);
 };
 <span>Window</span> includes <span>GlobalEventHandlers</span>;
 <span>Window</span> includes <span>WindowEventHandlers</span>;
 
-callback <dfn>FrameRequestCallback</dfn> = void (<span>DOMHighResTimeStamp</span> time);</code></pre>
+callback <dfn>FrameRequestCallback</dfn> = void (<span>DOMHighResTimeStamp</span> time);
+
+dictionary <dfn>WindowPostMessageOptions</dfn> {
+  USVString targetOrigin = "/";
+  sequence&lt;<span data-x="idl-object">object</span>&gt; transfer = [];
+};</code></pre>
 
 <!-- for more features to add here, look here:
  http://msdn.microsoft.com/workshop/author/dhtml/reference/objects/obj_window.asp
@@ -95356,10 +95362,9 @@ function receiver(e) {
 
   <dl class="domintro">
 
-   <dt><var>window</var> . <code subdfn data-x="dom-window-postMessage">postMessage</code>(<var>message</var>, <var>targetOrigin</var> [, <var>transfer</var> ] )</dt>
+   <dt><var>window</var> . <code subdfn data-x="dom-window-postMessage">postMessage</code>(<var>message</var>[, <var>transfer</var> ] [, options ])</dt>
 
    <dd>
-
     <p>Posts a message to the given window. Messages can be structured objects, e.g. nested objects
     and arrays, can contain JavaScript values (strings, numbers, <code>Date</code>
     objects, etc), and can contain certain data objects such as <code>File</code> <code>Blob</code>,
@@ -95368,17 +95373,30 @@ function receiver(e) {
     <p>Objects listed in <var>transfer</var> are transferred, not just cloned, meaning that
     they are no longer usable on the sending side.</p>
 
-    <p>If the origin of the target window doesn't match the given origin, the message is discarded,
-    to avoid information leakage. To send the message to the target regardless of origin, set the
-    target origin to "<code data-x="">*</code>". To restrict the message to same-origin targets only,
-    without needing to explicitly state the origin, set the target origin to "<code
-    data-x="">/</code>".</p>
+    <p>A target origin can be specified using the <code data-x="">targetOrigin</code> member of
+    <var>options</var>. If not provided, it defaults to "<code data-x="">/</code>". This restricts
+    the message to same-origin targets only.</p>
+
+    <p>This is an alternate version of postMessage where the target origin is specified as a
+    parameter. Calling <code data-x="">window.postMessage(message, target, transfer)</code> is
+    equivalent to <code data-x="">window.postMessage(message, transfer, {targetOrigin:
+    target})</code>.</p>
 
     <p>Throws a <span>"<code>DataCloneError</code>"</span> <code>DOMException</code> if
     <var>transfer</var> array contains duplicate objects or if <var>message</var> could not be
     cloned.</p>
 
    </dd>
+   <dt><var>window</var> . <code data-x="dom-window-postMessage">postMessage</code>(<var>message</var>, <var>targetOrigin</var> [, <var>transfer</var> ] )</dt>
+
+   <dd>
+
+    <p>This is an alternate version of postMessage where the target origin is specified as a
+    parameter. Calling <code data-x="">window.postMessage(message, target, transfer)</code> is
+    equivalent to <code data-x="">window.postMessage(message, transfer, {targetOrigin:
+    target})</code>.</p>
+
+   </dd>
 
   </dl>
 
@@ -95393,14 +95411,11 @@ function receiver(e) {
 
   <div w-nodev>
 
-  <p>The <dfn><code data-x="dom-window-postMessage">postMessage(<var>message</var>,
-  <var>targetOrigin</var>, <var>transfer</var>)</code></dfn> method, when invoked on a
-  <code>Window</code> object must run the following steps:</p>
+  <p>The <dfn>window post message steps</dfn>, given a <var>targetWindow</var>, <var>message</var>
+  and <var>options</var> are as follows:</p>
 
   <ol> <!-- a lot of this is similar or identical to port.postMessage -->
 
-   <li><p>Let <var>targetWindow</var> be this <code>Window</code> object.</p>
-
    <li><p>Let <var>targetRealm</var> be <var>targetWindow</var>'s <span
    data-x="concept-global-object-realm">Realm</span>.</p></li>
 
@@ -95410,6 +95425,9 @@ function receiver(e) {
    window, in same-origin cases. See discussion at
    https://github.com/whatwg/html/issues/1542#issuecomment-233502636 -->
 
+   <li><p>Let <var>targetOrigin</var> be the value of <var>options</var>'s <code
+   data-x="">targetOrigin</code> member.</p></li>
+
    <li><p>If <var>targetOrigin</var> is a single U+002F SOLIDUS character (/), then set
    <var>targetOrigin</var> to <var>incumbentSettings</var>'s <span
    data-x="concept-settings-object-origin">origin</span>.</p>
@@ -95430,6 +95448,9 @@ function receiver(e) {
     </ol>
    </li>
 
+   <li><p>Let <var>transfer</var> be the value of <var>options</var>'s <code
+   data-x="">transfer</code> member.</p></li>
+
    <li><p>Let <var>serializeWithTransferResult</var> be
    <span>StructuredSerializeWithTransfer</span>(<var>message</var>, <var>transfer</var>). Rethrow
    any exceptions.</p></li>
@@ -95483,6 +95504,36 @@ function receiver(e) {
    </li>
   </ol>
 
+  <p>The <dfn><code data-x="dom-window-postMessage-options">postMessage(<var>message</var>,
+  <var>options</var>)</code></dfn> method, when invoked on a
+  <code>Window</code> object must run the following steps:</p>
+  <ol>
+   <li><p>Let <var>targetWindow</var> be this <code>Window</code> object.</p></li>
+
+   <li><p>Run the <span>window post message steps</span> providing <var>targetWindow</var>,
+   <var>message</var> and <var>options</var>.</p></li>
+  </ol>
+
+  <p>The <dfn><code data-x="dom-window-postMessage">postMessage(<var>message</var>,
+  <var>targetOrigin</var>, <var>transfer</var>)</code></dfn> method, when invoked on a
+  <code>Window</code> object must run the following steps:</p>
+
+  <ol>
+   <li><p>Let <var>targetWindow</var> be this <code>Window</code> object.</p></li>
+
+   <li><p>Let <var>options</var> be a new instance of <code>WindowPostMessageOptions</code>
+   object.</p></li>
+
+   <li><p>Set <var>options</var>'s <code data-x="">targetOrigin</code> member to be
+   <var>targetOrigin</var>.</p></li>
+
+   <li><p>Set <var>options</var>'s <code data-x="">transfer</code> member to be
+   <var>transfer</var>.</p></li>
+
+   <li><p>Run the <span>window post message steps</span> providing
+   <var>targetWindow</var>, <var>message</var> and <var>options</var>.</p></li>
+  </ol>
+
   </div>