Set request's reload-navigation flag for reloads

See w3c/ServiceWorker#1167 for the discussion that led to this change and whatwg/fetch#685 for the infrastructure in Fetch this builds upon.

Tests: web-platform-tests/wpt#10192.

source

@@ -2819,6 +2819,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
        <li><dfn data-x="concept-request-nonce-metadata" data-x-href="https://fetch.spec.whatwg.org/#concept-request-nonce-metadata">cryptographic nonce metadata</dfn></li>
        <li><dfn data-x="concept-request-integrity-metadata" data-x-href="https://fetch.spec.whatwg.org/#concept-request-integrity-metadata">integrity metadata</dfn></li>
        <li><dfn data-x="concept-request-parser-metadata" data-x-href="https://fetch.spec.whatwg.org/#concept-request-parser-metadata">parser metadata</dfn></li>
+       <li><dfn data-x="concept-request-reload-navigation-flag" data-x-href="https://fetch.spec.whatwg.org/#concept-request-reload-navigation-flag">reload-navigation flag</dfn></li>
       </ul>
      </li>
     </ul>
@@ -81818,6 +81819,10 @@ interface <dfn>Location</dfn> { // but see also <a href="#the-location-interface
    data-x="concept-request">request</span> whose <span data-x="concept-request-url">url</span> is
    <var>resource</var>.</p></li>
 
+   <li><p>If <var>resource</var> is a <span data-x="concept-request">request</span> and this is
+   a <dfn>reload-triggered navigation</dfn>, then set <var>resource</var>'s <span
+   data-x="concept-request-reload-navigation-flag">reload-navigation flag</span>.
+
    <li id="sandboxLinks">
     <p>If the <span>source browsing context</span> is not <span>allowed to navigate</span>
     <var>browsingContext</var>, then:</p>
@@ -81855,7 +81860,7 @@ interface <dfn>Location</dfn> { // but see also <a href="#the-location-interface
    <span>prompt to unload</span> algorithm.</p></li>
    <!-- https://software.hixie.ch/utilities/js/live-dom-viewer/?saved=1946 to 1955 -->
 
-   <li id="navigate-fragid-step"><p>If this is not a <dfn>reload-triggered navigation</dfn>,
+   <li id="navigate-fragid-step"><p>If this is not a <span>reload-triggered navigation</span>,
    <var>resource</var> is a <span data-x="concept-request">request</span>, <var>resource</var>'s
    <span data-x="concept-request-url">url</span> <span data-x="concept-url-equals">equals</span>
    <var>browsingContext</var>'s <span>active document</span>'s <span
@@ -121510,6 +121515,7 @@ INSERT INTERFACES HERE
   Yoav Weiss,
   Yonathan Randolph,
   Yury Delendik,
+  平野裕 (Yutaka Hirano)
   Yuzo Fujishima,
   Zhenbin Xu,
   &#24352;&#26234;&#24378; (Zhiqiang Zhang),