Revamp base URL change processing

This removes the dependency on two concepts supposedly defined in DOM, that have not existed for many years. Instead, we have HTML directly call into the new "respond to base URL changes" steps, when mutations happen to a Document that would cause the base URL to change.

Also reorganizes some of the base URL stuff to stick together, instead of being mixed between "Dynamic changes to base URLs" and "Terminology".

Closes whatwg/dom#61.

Author: domenic

source

@@ -3312,7 +3312,6 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
                        <dfn data-x="concept-node-clone-parent" data-x-href="https://dom.spec.whatwg.org/#clone-a-node-parent"><var>parent</var></dfn>, and
                        <dfn data-x="concept-node-clone-fallbackRegistry" data-x-href="https://dom.spec.whatwg.org/#clone-a-node-fallbackregistry"><var>fallbackRegistry</var></dfn>, and the concept of
                        <dfn data-x="concept-node-clone-ext" data-x-href="https://dom.spec.whatwg.org/#concept-node-clone-ext">cloning steps</dfn></li>
-     <li>The concept of <dfn>base URL change steps</dfn> and the definition of what happens when an element is <dfn>affected by a base URL change</dfn></li>
      <li>The concept of an element's <dfn data-x="concept-id" data-x-href="https://dom.spec.whatwg.org/#concept-id">unique identifier (ID)</dfn></li>
      <li>The concept of an element's <dfn data-x="concept-class" data-x-href="https://dom.spec.whatwg.org/#concept-class">classes</dfn></li>
      <li>The term <dfn data-x="concept-supported-tokens" data-x-href="https://dom.spec.whatwg.org/#concept-supported-tokens">supported tokens</dfn></li>
@@ -7212,6 +7211,8 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
   data-x="strip leading and trailing ASCII whitespace">stripping leading and trailing ASCII
   whitespace</span> from it, it is a <span>valid non-empty URL</span>.</p>
 
+  <hr>
+
   <p>This specification defines the URL <dfn><code>about:legacy-compat</code></dfn> as a reserved,
   though unresolvable, <code data-x="about protocol">about:</code> URL, for use in <span
   data-x="syntax-doctype">DOCTYPE</span>s in <span>HTML documents</span> when needed for
@@ -7227,46 +7228,6 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
   document"><code>iframe</code> <code data-x="attr-iframe-srcdoc">srcdoc</code> documents</span>.
   <ref>ABOUT</ref></p>
 
-  <p>The <dfn>fallback base URL</dfn> of a <code>Document</code> object <var>document</var> is the
-  <span>URL record</span> obtained by running these steps:</p>
-
-  <ol>
-   <li>
-    <p>If <var>document</var> is <span data-x="an iframe srcdoc document">an <code>iframe</code>
-    <code data-x="attr-iframe-srcdoc">srcdoc</code> document</span>, then:</p>
-
-    <ol>
-     <li><p><span>Assert</span>: <var>document</var>'s <span
-     data-x="concept-document-about-base-url">about base URL</span> is non-null.</p></li>
-
-     <li><p>Return <var>document</var>'s <span data-x="concept-document-about-base-url">about base
-     URL</span>.</p></li>
-    </ol>
-   </li>
-
-   <li><p>If <var>document</var>'s <span data-x="concept-document-url">URL</span> <span>matches
-   <code>about:blank</code></span> and <var>document</var>'s <span
-   data-x="concept-document-about-base-url">about base URL</span> is non-null, then return
-   <var>document</var>'s <span data-x="concept-document-about-base-url">about base URL</span>.</p></li>
-
-   <!-- https://www.hixie.ch/tests/adhoc/dom/level0/history/pushState/001/ -->
-
-   <li><p>Return <var>document</var>'s <span data-x="concept-document-url">URL</span>.</p></li>
-  </ol>
-
-  <p>The <dfn export>document base URL</dfn> of a <code>Document</code> object is the
-  <span>URL record</span> obtained by running these steps:</p>
-
-  <ol>
-   <li><p>If there is no <code>base</code> element that has an <code
-   data-x="attr-base-href">href</code> attribute in the <code>Document</code>, then return the
-   <code>Document</code>'s <span>fallback base URL</span>.</p></li>
-
-   <li><p>Otherwise, return the <span>frozen base URL</span> of the first <code>base</code> element
-   in the <code>Document</code> that has an <code data-x="attr-base-href">href</code> attribute, in
-   <span>tree order</span>.</p></li>
-  </ol>
-
   <hr>
 
   <p>A <span>URL</span> <dfn>matches <code>about:blank</code></dfn> if its <span
@@ -7374,58 +7335,82 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
 
   <div w-nodev>
 
-  <h4>Dynamic changes to base URLs</h4>
+  <h4>Document base URLs</h4>
 
-  <p>When a document's <span>document base URL</span> changes, all elements in that document are
-  <span>affected by a base URL change</span>.</p>
+  <p>The <dfn export>document base URL</dfn> of a <code>Document</code> <var>document</var> is the
+  <span>URL record</span> obtained by running these steps:</p>
 
-  <p>The following are <span>base URL change steps</span>, which run when an element is
-  <span>affected by a base URL change</span> (as defined by <cite>DOM</cite>):</p>
+  <ol>
+   <li><p>If <var>document</var> has no <span>descendant</span> <code>base</code> element that has
+   an <code data-x="attr-base-href">href</code> attribute, then return <var>document</var>'s
+   <span>fallback base URL</span>.</p></li>
 
-  <dl class="switch">
+   <li><p>Otherwise, return the <span>frozen base URL</span> of the first <code>base</code> element
+   in <var>document</var> that has an <code data-x="attr-base-href">href</code> attribute, in
+   <span>tree order</span>.</p></li>
+  </ol>
 
-   <dt>If the element creates a <span>hyperlink</span></dt>
+  <p>The <dfn>fallback base URL</dfn> of a <code>Document</code> object <var>document</var> is the
+  <span>URL record</span> obtained by running these steps:</p>
 
-   <dd>
-    <p>If the <span>URL</span> identified by the hyperlink is being shown to the user, or if any
-    data derived from that <span>URL</span> is affecting the display, then the <code
-    data-x="attr-hyperlink-href">href</code> attribute's value should be <span
-    data-x="encoding-parsing a URL">reparsed</span>, relative to the element's <span>node
-    document</span> and the UI updated appropriately.</p>
+  <ol>
+   <li>
+    <p>If <var>document</var> is <span data-x="an iframe srcdoc document">an <code>iframe</code>
+    <code data-x="attr-iframe-srcdoc">srcdoc</code> document</span>:</p>
 
-    <p class="example">For example, the CSS <code data-x="selector-link">:link</code>/<code
-    data-x="selector-visited">:visited</code> <span data-x="pseudo-class">pseudo-classes</span>
-    might have been affected.</p>
+    <ol>
+     <li><p><span>Assert</span>: <var>document</var>'s <span
+     data-x="concept-document-about-base-url">about base URL</span> is non-null.</p></li>
 
-    <p>If the hyperlink has a <code data-x="attr-hyperlink-ping">ping</code> attribute and its
-    <span data-x="URL">URL(s)</span> are being shown to the user, then the <code
-    data-x="attr-hyperlink-ping">ping</code> attribute's tokens should be <span
-    data-x="encoding-parsing a URL">reparsed</span>, relative to the element's <span>node
-    document</span> and the UI updated appropriately.</p>
-   </dd>
+     <li><p>Return <var>document</var>'s <span data-x="concept-document-about-base-url">about base
+     URL</span>.</p></li>
+    </ol>
+   </li>
 
-   <dt>If the element is a <code>q</code>, <code>blockquote</code>, <code>ins</code>, or
-   <code>del</code> element with a <code data-x="">cite</code> attribute</dt>
+   <li><p>If <var>document</var>'s <span data-x="concept-document-url">URL</span> <span>matches
+   <code>about:blank</code></span> and <var>document</var>'s <span
+   data-x="concept-document-about-base-url">about base URL</span> is non-null, then return
+   <var>document</var>'s <span data-x="concept-document-about-base-url">about base
+   URL</span>.</p></li>
 
-   <dd>
-    <p>If the <span>URL</span> identified by the <code data-x="">cite</code> attribute is being
-    shown to the user, or if any data derived from that <span>URL</span> is affecting the display,
-    then the <code data-x="">cite</code> attribute's value should be <span data-x="encoding-parsing
-    a URL">reparsed</span>, relative to the element's <span>node document</span> and the UI updated
-    appropriately.</p>
-   </dd>
+   <!-- https://www.hixie.ch/tests/adhoc/dom/level0/history/pushState/001/ -->
 
-   <dt>Otherwise</dt>
+   <li><p>Return <var>document</var>'s <span data-x="concept-document-url">URL</span>.</p></li>
+  </ol>
 
-   <dd>
-    <p>The element is not directly affected.</p>
+  <hr>
 
-    <p class="example">For instance, changing the base URL doesn't affect the image displayed by
-    <code>img</code> elements, although subsequent accesses of the <code
-    data-x="dom-img-src">src</code> IDL attribute from script will return a new <span>absolute
-    URL</span> that might no longer correspond to the image being shown.</p>
-   </dd>
-  </dl>
+  <p>To <dfn>set the URL</dfn> for a <code>Document</code> <var>document</var> to a <span>URL
+  record</span> <var>url</var>:</p>
+
+  <ol>
+   <li><p>Set <var>document</var>'s <span data-x="concept-document-url">URL</span> to
+   <var>url</var>.</p></li>
+
+   <li><p><span>Respond to base URL changes</span> given <var>document</var>.</p></li>
+  </ol>
+
+  <p id="dynamic-changes-to-base-urls">To <dfn>respond to base URL changes</dfn> for a
+  <code>Document</code> <var>document</var>:</p>
+
+  <ol>
+   <li><p>The user agent should update any user interface elements which are displaying affected
+   URLs, or data derived from such URLs, to the user. Examples of such user interface elements would
+   be a status bar that displays a <span>hyperlink</span>'s <span
+   data-x="concept-hyperlink-url">url</span>, or some user interface which displays the URL
+   specified by a <code>q</code>, <code>blockquote</code>, <code>ins</code>, or <code>del</code>
+   element's <code data-x="">cite</code> attribute.</p></li>
+
+   <li><p>Ensure that the CSS <code data-x="selector-link">:link</code>/<code
+   data-x="selector-visited">:visited</code>/etc. <span data-x="pseudo-class">pseudo-classes</span>
+   are updated appropriately.</p></li>
+  </ol>
+
+  <p class="example" id="example-base-url-change-img-unaffected">This means that changing the base
+  URL doesn't affect, for example, the image displayed by <code>img</code> elements. Thus,
+  subsequent accesses of the <code data-x="dom-img-src">src</code> IDL attribute from script will
+  return a new <span>absolute URL</span> that might no longer correspond to the image being
+  shown.</p>
 
   </div>
 
@@ -15345,6 +15330,8 @@ interface <dfn interface>HTMLBaseElement</dfn> : <span>HTMLElement</span> {
    </li>
 
    <li><p>Set <var>element</var>'s <span>frozen base URL</span> to <var>urlRecord</var>.</p></li>
+
+   <li><p><span>Respond to base URL changes</span> given <var>document</var>.</p></li>
   </ol>
 
   <p>The <dfn attribute for="HTMLBaseElement"><code data-x="dom-base-href">href</code></dfn> IDL
@@ -103684,8 +103671,7 @@ location.href = '#foo';</code></pre>
    state</span> given <var>document</var> and <var>newEntry</var>.</p></li>
 
    <li>
-    <p>Set <var>document</var>'s <span data-x="concept-document-url">URL</span> to
-    <var>newURL</var>.</p>
+    <p><span>Set the URL</span> given <var>document</var> to <var>newURL</var>.</p>
 
     <p class="note">Since this is neither a <span data-x="navigate">navigation</span> nor a <span
     data-x="traverse the history by a delta">history traversal</span>, it does not cause a <code