Remove XML loading's namespace-based dispatching

It's not implemented and complicates navigation.

Closes #2656.

source

@@ -82733,11 +82733,8 @@ interface <dfn>Location</dfn> { // but see also <a href="#the-location-interface
      <dt>an <span>XML MIME type</span> that is not an <span>explicitly supported XML MIME
      type</span></dt>
 
-     <dd>Follow the steps given in the <span data-x="navigate-xml">XML document</span> section. If
-     that section determines that the content is <em>not</em> to be displayed as a generic XML
-     document, then proceed to the next step in this overall set of steps. Otherwise, once the steps
-     given in the <span data-x="navigate-xml">XML document</span> section have completed,
-     return.</dd>
+     <dd>Follow the steps given in the <span data-x="navigate-xml">XML document</span> section, and
+     then, once they have completed, return.</dd>
 
      <dt>a <span>JavaScript MIME type</span></dt>
      <dt>a <span>JSON MIME type</span> that is not an <span>explicitly supported JSON MIME
@@ -83165,19 +83162,12 @@ interface <dfn>Location</dfn> { // but see also <a href="#the-location-interface
   data-x="">&lt;?xml-stylesheet?></code> PIs) will be fetched from the network and cannot be
   cached.</p><!-- v2: fix this somehow -->
 
-  <p>User agents may examine the namespace of the root <code>Element</code> node of this
-  <code>Document</code> object to perform namespace-based dispatch to alternative processing tools,
-  e.g. determining that the content is actually a syndication feed and passing it to a feed handler.
-  If such processing is to take place, abort the steps in this section, and jump to <a
-  href="#navigate-non-Document">the next step</a> (labeled <i>non-document content</i>) in the
-  <span>navigate</span> steps above.</p>
+  <p>Then, with the newly created <code>Document</code>, the user agent must <span>update the
+  session history with the new page</span>. User agents may do this before the complete document has
+  been parsed (thus achieving <i>incremental rendering</i>), and must do this before any scripts are
+  to be executed.</p>
 
-  <p>Otherwise, then, with the newly created <code>Document</code>, the user agent must <span>update
-  the session history with the new page</span>. User agents may do this before the complete document
-  has been parsed (thus achieving <i>incremental rendering</i>), and must do this before any scripts
-  are to be executed.</p>
-
-  <p>Error messages from the parse process (e.g. XML namespace well-formedness errors) may be
+  <p>Error messages from the parse process (e.g., XML namespace well-formedness errors) may be
   reported inline by mutating the <code>Document</code>.</p>