fix a few other issues

fetch.bs

@@ -3747,7 +3747,8 @@ defined here as the model defined in HTTP is not compatible with web content. [[
 <div algorithm>
 <p>To
 <dfn export for="header list" lt="extract a MIME type|extracting a MIME type" id=concept-header-extract-mime-type>extract a MIME type</dfn>
-from a <a for=/>header list</a> <var>headers</var>, run these steps:
+from a <a for=/>header list</a> <var>headers</var>, run these steps. They return failure or a
+<a for=/>MIME type</a>.
 
 <ol>
  <li><p>Let <var>charset</var> be null.
@@ -4773,7 +4774,7 @@ steps:
        <a for="header list">extracting a MIME type</a> from <var>response</var>'s
        <a for=response>header list</a>.
 
-       <li><p>If <var>mimeType</var> is non-null, then set <var>bodyInfo</var>'s
+       <li><p>If <var>mimeType</var> is not failure, then set <var>bodyInfo</var>'s
        <a for="response body info">content type</a> to the result of
        <a>minimizing a supported MIME type</a> given <var>mimeType</var>.
       </ol>
@@ -7186,10 +7187,12 @@ due course.
  <li><p>Otherwise, set <var>headers</var> to <var>requestOrResponse</var>'s
  <a for=Response>response</a>'s <a for=response>header list</a>.
 
- <li><p>Let <var>mimeTypeInHeaders</var> be the result of
- <a for="header list">extracting a MIME type</a> from <var>headers</var>.
+ <li><p>Let <var>mimeType</var> be the result of <a for="header list">extracting a MIME type</a>
+ from <var>headers</var>.
+
+ <li><p>If <var>mimeType</var> is failure, then return null.
 
- <li><p>Return <var>mimeTypeInHeaders</var>.
+ <li><p>Return <var>mimeType</var>.
 </ol>
 </div>
 
@@ -7249,7 +7252,8 @@ of running <a for=Body>consume body</a> with <a>this</a> and the following step
 <p>The <dfn method for=Body><code>blob()</code></dfn> method steps are to return the result
 of running <a for=Body>consume body</a> with <a>this</a> and the following step given a
 <a for=/>byte sequence</a> <var>bytes</var>: return a {{Blob}} whose contents are <var>bytes</var>
-and whose {{Blob/type}} attribute is to <a for=Body>get the MIME type</a> with <a>this</a>.
+and whose {{Blob/type}} attribute is the result of <a for=Body>get the MIME type</a> with
+<a>this</a>.
 <!-- This is wrong. It should really set an underlying concept to this. -->
 </div>