Define the HTTP Refresh header

Fixes https://www.w3.org/Bugs/Public/show_bug.cgi?id=28339 and fixes https://www.w3.org/Bugs/Public/show_bug.cgi?id=28563.

Tests: web-platform-tests/wpt#6606.

Follow-up: #2900.

source

@@ -14290,20 +14290,25 @@ people expect to have work and what is necessary.
     <div w-nodev>
 
     <ol>
-     <!-- TESTS: https://www.hixie.ch/tests/adhoc/html/meta/refresh/ -->
-     <!-- https://software.hixie.ch/utilities/js/live-dom-viewer/?saved=734 -->
-     <li><p>Let <var>document</var> be the <code>meta</code> element's <span>node
-     document</span>.</p></li>
-
-     <li><p>If <var>document</var>'s <span>will declaratively refresh</span> is true, then
-     return.</p></li>
-
      <li><p>If the <code>meta</code> element has no <code data-x="attr-meta-content">content</code>
      attribute, or if that attribute's value is the empty string, then return.</p></li>
 
      <li><p>Let <var>input</var> be the value of the element's <code
      data-x="attr-meta-content">content</code> attribute.</p></li>
 
+     <li><p>Run the <span>shared declarative refresh steps</span> with the <code>meta</code>
+     element's <span>node document</span>, <var>input</var>, and the <code>meta</code>
+     element.</p></li>
+    </ol>
+
+    <p>The <dfn>shared declarative refresh steps</dfn>, given a <code>Document</code> object
+    <var>document</var>, string <var>input</var>, and optionally a <code>meta</code> element
+    <var>meta</var>, are as follows:</p>
+
+    <ol>
+     <li><p>If <var>document</var>'s <span>will declaratively refresh</span> is true, then
+     return.</p></li>
+
      <li><p>Let <var>position</var> point at the first <span>code point</span> of
      <var>input</var>.</p></li>
 
@@ -14410,12 +14415,12 @@ people expect to have work and what is necessary.
       <ul>
        <li>
         <p>After the refresh has come due (as defined below), if the user has not canceled the
-        redirect and <var>document</var>'s <span>active sandboxing flag set</span> does not have the
-        <span>sandboxed automatic features browsing context flag</span> set, <span
-        data-x="navigate">navigate</span><!--DONAV meta refresh--> <var>document</var>'s <span
-        data-x="concept-document-bc">browsing context</span> to <var>urlRecord</var>, with
-        <span>replacement enabled</span>, and with <var>document</var>'s <span
-        data-x="concept-document-bc">browsing context</span> as the <span>source browsing
+        redirect and, if <var>meta</var> is given, <var>document</var>'s <span>active sandboxing
+        flag set</span> does not have the <span>sandboxed automatic features browsing context
+        flag</span> set, then <span data-x="navigate">navigate</span><!--DONAV meta refresh-->
+        <var>document</var>'s <span data-x="concept-document-bc">browsing context</span> to
+        <var>urlRecord</var>, with <span>replacement enabled</span>, and with <var>document</var>'s
+        <span data-x="concept-document-bc">browsing context</span> as the <span>source browsing
         context</span>.</p>
 
         <p>For the purposes of the previous paragraph, a refresh is said to have come due as soon as
@@ -14427,20 +14432,22 @@ people expect to have work and what is necessary.
          preferences.</li>
          <!-- https://software.hixie.ch/utilities/js/live-dom-viewer/?saved=774 -->
 
-         <li>At least <var>time</var> seconds have elapsed since the <code>meta</code> element was
-         <span data-x="node is inserted into a document">inserted into the document</span>
-         <var>document</var>, adjusted to take into account user or user agent preferences.</li>
+         <li>If <var>meta</var> is given, at least <var>time</var> seconds have elapsed since
+         <var>meta</var> was <span data-x="node is inserted into a document">inserted into the
+         document</span> <var>document</var>, adjusted to take into account user or user agent
+         preferences.</li>
          <!-- https://software.hixie.ch/utilities/js/live-dom-viewer/?saved=772 -->
         </ul>
 
-        <p class="note">It is important to use <var>document</var> here, and not the
-        <code>meta</code> element's <span>node document</span>, as that might have changed between
-        the initial set of steps and the refresh coming due.</p>
+        <p class="note">It is important to use <var>document</var> here, and not <var>meta</var>'s
+        <span>node document</span>, as that might have changed between the initial set of steps and
+        the refresh coming due and <var>meta</var> is not always given (in case of the HTTP
+        `<code data-x="http-refresh">Refresh</code>` header).</p>
        </li>
 
        <li><p>Provide the user with an interface that, when selected, <span
        data-x="navigate">navigates</span><!--DONAV meta refresh--> a <span>browsing context</span>
-       to <var>urlRecord</var>, with the <code>Document</code>'s <span
+       to <var>urlRecord</var>, with <var>document</var>'s <span
        data-x="concept-document-bc">browsing context</span> as the <span>source browsing
        context</span>.</p></li>
 
@@ -82324,6 +82331,22 @@ State: &lt;OUTPUT NAME=I>1&lt;/OUTPUT> &lt;INPUT VALUE="Increment" TYPE=BUTTON O
      <li><p><span>Implement the sandboxing</span> for the <code>Document</code>.</p></li>
 
      <li><p><span>Set the allow* flags</span> for the <code>Document</code>.</p></li>
+
+     <li>
+      <p>If <var>response</var> has a `<code data-x="http-refresh">Refresh</code>` header, then:</p>
+
+      <ol>
+       <li><p class="&#x0058;&#x0058;&#x0058;"><a
+       href="https://github.com/whatwg/html/issues/2900">Multiple `<code
+       data-x="http-refresh">Refresh</code>` headers</a>.</p></li>
+
+       <li><p>Let <var>value</var> be the value of the header with each byte mapped to a code point
+       of equal value.</p></li>
+
+       <li><p>Run the <span>shared declarative refresh steps</span> with the <code>Document</code>
+       and <var>value</var>.</p></li>
+      </ol>
+     </li>
     </ol>
    </li>
 
@@ -115353,6 +115376,29 @@ interface <dfn>External</dfn> {
   </dl>
 
 
+  <h3>`<dfn><code data-x="http-refresh">Refresh</code></dfn>`</h3>
+
+  <p>This section describes a header for registration in the Permanent Message Header Field
+  Registry. <ref spec=RFC3864></p>
+
+  <dl>
+   <dt>Header field name:</dt>
+   <dd>Refresh</dd>
+   <dt>Applicable protocol:</dt>
+   <dd>http</dd>
+   <dt>Status:</dt>
+   <dd>standard</dd>
+   <dt>Author/Change controller:</dt>
+   <dd>WHATWG</dd>
+   <dt>Specification document(s):</dt>
+   <dd>
+    This document is the relevant specification.
+   </dd>
+   <dt>Related information:</dt>
+   <dd>None.</dd>
+  </dl>
+
+
   <h3>`<dfn><code data-x="http-last-event-id">Last-Event-ID</code></dfn>`</h3>
 
   <p>This section describes a header for registration in the Permanent Message Header Field