Editorial: add <div algorithm> wrappers to data URLs

Closes #1526 as the <div algorithm> wrappers are everywhere now.

Also address some Reffy-related failures and markup errors.

Co-authored-by: Anne van Kesteren <[email protected]>

Author: dlrobertson

fetch.bs

@@ -114,6 +114,7 @@ urlPrefix:https://tc39.es/ecma262/#;type:dfn;spec:ecma-262
 </pre>
 
 <pre class=link-defaults>
+spec:dom; type:dfn; text:element
 spec:infra; type:dfn; text:implementation-defined
 </pre>
 
@@ -867,7 +868,7 @@ directly. Use <a for="header list">get, decode, and split</a> instead.
 <a lt=name for=header>names</a> <var>headerNames</var>, run these steps:
 
 <ol>
- <li><p>Let <var>headerNamesSet</var> be a new <a for/>ordered set</a>.
+ <li><p>Let <var>headerNamesSet</var> be a new <a for=/>ordered set</a>.
 
  <li><p><a for=list>For each</a> <var>name</var> of <var>headerNames</var>, <a for=set>append</a>
  the result of <a lt=byte-lowercased>byte-lowercasing</a> <var>name</var> to
@@ -1136,7 +1137,7 @@ is a <a>byte-case-insensitive</a> match for one of
 </ul>
 
 <div algorithm>
-<p>To determine whether a <a for/>header</a> (<var>name</var>, <var>value</var>) is a
+<p>To determine whether a <a for=/>header</a> (<var>name</var>, <var>value</var>) is a
 <dfn noexport>no-CORS-safelisted request-header</dfn>, run these steps:
 
 <ol>
@@ -8484,6 +8485,7 @@ that RFC's normative processing requirements to be compatible with deployed cont
 <dfn for="data: URL struct">MIME type</dfn> (a <a for=/>MIME type</a>) and a
 <dfn for="data: URL struct">body</dfn> (a <a>byte sequence</a>).
 
+<div algorithm>
 <p>The <dfn export><code>data:</code> URL processor</dfn> takes a <a for=/>URL</a>
 <var>dataURL</var> and then runs these steps:
 
@@ -8545,6 +8547,7 @@ that RFC's normative processing requirements to be compatible with deployed cont
  <a for="data: URL struct">MIME type</a> is <var>mimeTypeRecord</var> and
  <a for="data: URL struct">body</a> is <var>body</var>.
 </ol>
+</div>