Fire visibilitychange events explicitly

Fire the event when unloading or traversing history, instead of relying on hooks in other specs.

See w3c/page-visibility#51 and w3c/page-visibility#73.

Author: noamr

source

@@ -9315,6 +9315,7 @@ partial interface <dfn id="document" data-lt="">Document</dfn> {
 
   // special <span>event handler IDL attributes</span> that only apply to Document objects
   [<span>LegacyLenientThis</span>] attribute <span>EventHandler</span> <span data-x="handler-onreadystatechange">onreadystatechange</span>;
+  attribute <span>EventHandler</span> <span data-x="handler-onvisibilitychange">onvisibilitychange</span>;
 
   // <a href="#Document-partial">also has obsolete members</a>
 };
@@ -88453,13 +88454,9 @@ new PaymentRequest(&hellip;); // Allowed to use
 
        <li><p>Set <var>newDocument</var>'s <span>page showing</span> flag to true.</p></li>
 
-       <li>
-        <p>Run any <dfn>session history document visibility change steps</dfn> for
-        <var>newDocument</var> that are defined by <span>other applicable specifications</span>.</p>
-
-        <p class="note">This is specifically intended for use by <cite>Page Visibility</cite>. <ref
-        spec=PAGEVIS></p>
-       </li>
+       <li><p>Fire an event named <code data-x="event-visibilitychange">visibilitychange</code> at
+       <var>newDocument</var>, with its <code data-x="dom-Event-bubbles">bubbles</code> attribute
+       initialized to true.</p></li>
 
        <li><p><span>Fire a page transition event</span> named <code
        data-x="event-pageshow">pageshow</code> at <var>newDocument</var>'s <span>relevant global
@@ -88912,40 +88909,36 @@ dictionary <dfn dictionary>PageTransitionEventInit</dfn> : <span>EventInit</span
 
    <li><p>Increase <var>document</var>'s <span>unload counter</span> by 1.</p></li>
 
-   <li><p>If <var>document</var>'s <span>page showing</span> flag is false, then jump to the
-   step labeled <i>unload event</i> below (i.e. skip firing the <code
-   data-x="event-pagehide">pagehide</code> event and don't rerun the <span>unloading document
-   visibility change steps</span>).</p></li>
-
-   <li><p>Set <var>document</var>'s <span>page showing</span> flag to false.</p></li>
-
    <li><p>If the user agent does not intend to keep <var>document</var> alive
    in a <span>session history entry</span> (such that it can be reused later on <span
    data-x="traverse the history">history traversal</span>), set <var>document</var>'s
    <i data-x="concept-document-salvageable">salvageable</i> state to false.</p></li>
 
-   <li><p><span>Fire a page transition event</span> named <code
-   data-x="event-pagehide">pagehide</code> at <var>document</var>'s <span>relevant global
-   object</span> with <var>document</var>'s <i data-x="concept-document-salvageable">salvageable</i>
-   state.</p></li>
-
    <li>
-    <p>Run any <dfn>unloading document visibility change steps</dfn> for <var>document</var> that
-    are defined by <span>other applicable specifications</span>.</p>
+    <p>If <var>document</var>'s <span>page showing</span> flag is true:</p>
 
-    <p class="note">This is specifically intended for use by <cite>Page Visibility</cite>.
-    <ref spec=PAGEVIS></p>
-   </li>
+    <ol>
+     <li><p>Set <var>document</var>'s <span>page showing</span> flag to false.</p></li>
+
+     <li><p><span>Fire a page transition event</span> named <code
+     data-x="event-pagehide">pagehide</code> at <var>document</var>'s <span>relevant global
+     object</span> with <var>document</var>'s <i
+     data-x="concept-document-salvageable">salvageable</i> state.</p></li>
+
+     <li><p>Fire an event named <code data-x="event-visibilitychange">visibilitychange</code> at
+     <var>newDocument</var>, with its <code data-x="dom-Event-bubbles">bubbles</code> attribute
+     initialized to true.</p></li>
+    </ol>
+  </li>
 
    <li><p>If <var>unloadTimingInfo</var> is not null, then set <var>unloadTimingInfo</var>'s
    <span>unload event start time</span> to the <span>current high resolution time</span> given
    <var>document</var>'s <span>relevant global object</span>.</p></li>
 
-   <li><p><i>Unload event</i>: If <var>document</var>'s <i
-   data-x="concept-document-salvageable">salvageable</i> state is false, then <span
-   data-x="concept-event-fire">fire an event</span> named <code data-x="event-unload">unload</code>
-   at <var>document</var>'s <span>relevant global object</span>, with <var>legacy target override
-   flag</var> set.</p></li>
+   <li><p>If <var>document</var>'s <i data-x="concept-document-salvageable">salvageable</i> state is
+   false, then <span data-x="concept-event-fire">fire an event</span> named
+   <code data-x="event-unload">unload</code> at <var>document</var>'s
+   <span>relevant global object</span>, with <var>legacy target override flag</var> set.</p></li>
 
    <li><p>If <var>unloadTimingInfo</var> is not null, then set <var>unloadTimingInfo</var>'s
    <span>unload event end time</span> to the <span>current high resolution time</span> given
@@ -95130,6 +95123,7 @@ typedef <span>OnBeforeUnloadEventHandlerNonNull</span>? <dfn typedef>OnBeforeUnl
     <tr><th><span data-x="event handlers">Event handler</span> <th><span>Event handler event type</span>
    <tbody>
     <tr><td><dfn attribute for="Document"><code data-x="handler-onreadystatechange">onreadystatechange</code></dfn> <td> <code data-x="event-readystatechange">readystatechange</code>
+    <tr><td><dfn attribute for="Document"><code data-x="handler-onvisibilitychange">onvisibilitychange</code></dfn> <td> <code data-x="event-visibilitychange">visibilitychange</code>
   </table>
 
 
@@ -125586,6 +125580,13 @@ INSERT INTERFACES HERE
      <td> <code>Window</code>
      <td> Fired at the <code>Window</code> object when the page is going away
 
+    <tr> <!-- visibilitychange -->
+     <td> <dfn event for="Document"><code data-x="event-visibilitychange">visibilitychange</code></dfn>
+     <td> <code>Event</code>
+     <td> <code>Document</code>
+     <td> Fired at the <code>Document</code> object when the page becomes visible or hidden to the
+     user. <ref spec=PAGEVIS>
+
   </table>
 
   <p class="note">See also <a href="#mediaevents">media element events</a> and <a