Use relevant settings object in protocol handlers

The test at https://url-parsing-entry-gjqursujea.now.sh/entry/entry.html
reveals that Firefox at least uses relevant for URL parsing. Boris says
that Firefox does something nonsensical for the origin check and that he
would prefer relevant or current.

Code inspection reveals that Blink and WebKit use relevant for both URL
parsing and origin checking:

- https://chromium.googlesource.com/chromium/src/+/ee94bde91c72a046bec15436d56cfe32bb0e524c/third_party/WebKit/Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp#71
- https://github.com/WebKit/webkit/blob/83624b838d4fa81df77060c51b09587169f8ff19/Source/WebCore/Modules/navigatorcontentutils/NavigatorContentUtils.cpp#L109

Edge does not support these methods.

Helps with whatwg#1431.

source

@@ -90734,16 +90734,17 @@ interface <dfn>NavigatorContentUtils</dfn> {
 
     <p>User agents must throw a <span>"<code>SyntaxError</code>"</span> <code>DOMException</code> if
     <span data-x="parse a url">parsing</span> the <var>url</var> argument relative to the
-    <span>entry settings object</span> is not successful.</p>
+    <span>relevant settings object</span> of this <code>NavigatorContentUtils</code> object is not
+    successful.</p>
 
     <p class="note">The <span>resulting URL string</span> would by definition not be a <span>valid
     URL</span> as it would include the string "<code data-x="">%s</code>" which is not a valid
     component in a URL.</p>
 
     <p>User agents must throw a <span>"<code>SecurityError</code>"</span> <code>DOMException</code>
     if the <span>resulting URL record</span> has an <span data-x="concept-url-origin">origin</span>
-    that differs from the <span>origin</span> specified by the <span>entry settings
-    object</span>.</p>
+    that differs from the <span>origin</span> specified by the <span>relevant settings object</span>
+    of this <code>NavigatorContentUtils</code> object.</p>
 
     <p class="note">This is forcibly the case if the <code data-x="">%s</code> placeholder is in the
     scheme, host, or port parts of the URL.</p>
@@ -90754,10 +90755,10 @@ interface <dfn>NavigatorContentUtils</dfn> {
     <p>When the user agent uses this handler, it must replace the first occurrence of the exact
     literal string "<code data-x="">%s</code>" in the <var>url</var> argument with an
     escaped version of the <span>absolute URL</span> of the content in question (as defined below),
-    then <span data-x="parse a url">parse</span> the resulting URL, relative to the <span>entry
-    settings object</span> at the time the <code
+    then <span data-x="parse a url">parse</span> the resulting URL, relative to the <span>relevant
+    settings object</span> of the <code>NavigatorContentUtils</code> object on which the <code
     data-x="dom-navigator-registerContentHandler">registerContentHandler()</code> or <code
-    data-x="dom-navigator-registerProtocolHandler">registerProtocolHandler()</code> methods were
+    data-x="dom-navigator-registerProtocolHandler">registerProtocolHandler()</code> method was
     invoked, and then <span>navigate</span><!--DONAV user--> an appropriate <span>browsing
     context</span> to the resulting URL.</p>
 
@@ -90993,14 +90994,14 @@ interface <dfn>NavigatorContentUtils</dfn> {
    <li><p>If the string does not contain the substring "<code data-x="">%s</code>", abort these
    steps. There's no matching handler.</p></li>
 
-   <li><p><span data-x="parse a URL">Parse</span> the string relative to the <span>entry settings
-   object</span>. If this fails, then throw a <span>"<code>SyntaxError</code>"</span>
-   <code>DOMException</code>.</p></li>
+   <li><p><span data-x="parse a URL">Parse</span> the string relative to the <span>relevant settings
+   object</span> of this <code>NavigatorContentUtils</code> object. If this fails, then throw a
+   <span>"<code>SyntaxError</code>"</span> <code>DOMException</code>.</p></li>
 
    <li><p>If the <span>resulting URL record</span>'s <span data-x="concept-url-origin">origin</span>
-   is not the <span>same origin</span> as the <span>origin</span> specified by the <span>entry
-   settings object</span>, throw a <span>"<code>SecurityError</code>"</span>
-   <code>DOMException</code>.</p></li>
+   is not the <span>same origin</span> as the <span>origin</span> of the <span>relevant settings
+   object</span> of this <code>NavigatorContentUtils</code> object, throw a
+   <span>"<code>SecurityError</code>"</span> <code>DOMException</code>.</p></li>
 
    <li><p>Return the <span>resulting URL string</span> as the result of preprocessing the
    argument.</p></li>