Also return an empty string value when a header has no value but is p…

…resent

fetch.bs

@@ -698,6 +698,19 @@ A: nosniff
 B: sniff
 A:
 </code></pre>
+  <tr>
+   <td>
+    <pre><code class=lang-http>
+A:
+B: sniff
+</code></pre>
+   <td>« "" »
+  <tr>
+   <td>
+    <pre><code class=lang-http>
+B: sniff
+</code></pre>
+   <td>null
   <tr>
    <td>
     <pre><code class=lang-http>A: text/html;", x/x</code></pre>
@@ -763,12 +776,12 @@ a <a for=/>header value</a> <var>value</var>, run these steps. They return a <a
  <li><p>Let <var>position</var> be a <a for=string>position variable</a> for <var>input</var>,
  initially pointing at the start of <var>input</var>.
 
- <li><p>Let <var>values</var> be a <a for=/>list</a> of <a for=/>strings</a>, initially empty.
+ <li><p>Let <var>values</var> be a <a for=/>list</a> of <a for=/>strings</a>, initially « ».
 
  <li><p>Let <var>temporaryValue</var> be the empty string.
 
  <li>
-  <p>While <var>position</var> is not past the end of <var>input</var>:
+  <p>While true:
 
   <ol>
    <li>
@@ -795,21 +808,13 @@ a <a for=/>header value</a> <var>value</var>, run these steps. They return a <a
 
    <li><p>Set <var>temporaryValue</var> to the empty string.
 
-   <li>
-    <p>If <var>position</var> is not past the end of <var>input</var>:
-
-    <ol>
-     <li><p><a for=/>Assert</a>: the <a for=/>code point</a> at <var>position</var> within
-     <var>input</var> is U+002C (,).
+   <li><p>If <var>position</var> is past the end of <var>input</var>, then return <var>values</var>.
 
-     <li><p>Advance <var>position</var> by 1.
+   <li><p><a for=/>Assert</a>: the <a for=/>code point</a> at <var>position</var> within
+   <var>input</var> is U+002C (,).
 
-     <li><p>If <var>position</var> is past the end of <var>input</var>, then <a for=list>append</a>
-     the empty string to <var>values</var>.
-    </ol>
+   <li><p>Advance <var>position</var> by 1.
   </ol>
-
- <li><p>Return <var>values</var>.
 </ol>
 
 <p class=note>Except for blessed call sites, the algorithm directly above is not to be invoked