Add Content Encoding response header to fetch.

Author: guohuideng2024

fetch.bs

@@ -370,6 +370,8 @@ following <a for=struct>items</a>: [[RESOURCE-TIMING]] [[NAVIGATION-TIMING]]
  <dd>A number.
  <dt><dfn export for="response body info">content type</dfn> (default the empty string)
  <dd>An <a for=/>ASCII string</a>.
+ <dt><dfn export for="response body info">content encoding</dfn> (default the empty string)
+ <dd>An <a for=/>ASCII string</a>.
 </dl>
 
 <div algorithm>
@@ -1132,6 +1134,7 @@ a <a>byte-case-insensitive</a> match for one of
  <li>`<code>Content-Language</code>`
  <li>`<code>Content-Length</code>`
  <li>`<code>Content-Type</code>`
+ <li>`<code>Content-Encoding</code>`
  <li>`<code>Expires</code>`
  <li>`<code>Last-Modified</code>`
  <li>`<code>Pragma</code>`
@@ -1147,6 +1150,7 @@ is a <a>byte-case-insensitive</a> match for one of
  <li>`<code>Accept-Language</code>`
  <li>`<code>Content-Language</code>`
  <li>`<code>Content-Type</code>`
+ <li>`<code>Content-Encoding</code>`
 </ul>
 
 <div algorithm>
@@ -3946,6 +3950,40 @@ Content-Type:
 </div>
 </div>
 
+<h3 id=content-encoding>`<code>Content-Encoding</code>` header</h3>
+
+<p>The `<code>Content-Encoding</code>` header is largely defined in HTTP. Its processing model is
+defined here as the model defined in HTTP is not compatible with web content. [[HTTP]]
+
+<div algorithm>
+<p>To <dfn export for="header list" lt="extract an encoding type|extracting an encoding type">
+extract an encoding type</dfn> from a <a for=/>header list</a> <var>headers</var>, run these steps:
+
+<ol>
+ <li><p>Let <var>values</var> be the result of
+ <a for="header list">getting, decoding, and splitting</a> `<code>Content-Encoding</code>` from
+ <var>headers</var>.
+
+ <li><p>If <var>values</var> is null, then return null.
+
+ <li><p>Let <var>candidateValue</var> be null.
+
+ <li>
+  <p><a for=list>For each</a> <var>value</var> of <var>values</var>:
+
+  <ol>
+   <li><p>If <var>candidateValue</var> is null, then set <var>candidateValue</var> to
+   <var>value</var>.
+
+   <li><p>Otherwise, if <var>value</var> is not <var>candidateValue</var>, return failure.
+  </ol>
+
+ <li><p>If <var>candidateValue</var> is the empty string or has a <a for=/>code point</a> that is
+ not an <a for=/>ASCII digit</a>, then return null.
+
+ <li><p>Return <var>candidateValue</var>, interpreted as a string.
+</ol>
+</div>
 
 <h3 id=x-content-type-options-header>`<code>X-Content-Type-Options</code>` header</h3>
 
@@ -9127,6 +9165,7 @@ Gavin Carothers,
 Glenn Maynard,
 Graham Klyne,
 Gregory Terzian,
+Guohui Deng,
 Hal Lockhart,
 Hallvord R. M. Steen,
 Harris Hancock,