Bug 1839315: part 2) Add fetchPriority attribute to HTMLLinkElement's DOM interface. r=necko-reviewers,webidl,saschanaz,valentin

Setting the internal priority depending on the `fetchPriority` will be
implemented in a following part.

Differential Revision: https://phabricator.services.mozilla.com/D189936

dom/html/HTMLLinkElement.cpp

@@ -49,7 +49,7 @@ namespace mozilla::dom {
 
 HTMLLinkElement::HTMLLinkElement(
     already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo)
-    : nsGenericHTMLElement(std::move(aNodeInfo)) {}
+    : nsGenericHTMLElementWithFetchPriorityAttribute(std::move(aNodeInfo)) {}
 
 HTMLLinkElement::~HTMLLinkElement() { SupportsDNSPrefetch::Destroyed(*this); }
 
@@ -165,8 +165,8 @@ bool HTMLLinkElement::ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
     }
   }
 
-  return nsGenericHTMLElement::ParseAttribute(aNamespaceID, aAttribute, aValue,
-                                              aMaybeScriptedPrincipal, aResult);
+  return nsGenericHTMLElementWithFetchPriorityAttribute::ParseAttribute(
+      aNamespaceID, aAttribute, aValue, aMaybeScriptedPrincipal, aResult);
 }
 
 void HTMLLinkElement::CreateAndDispatchEvent(const nsAString& aEventName) {

dom/html/HTMLLinkElement.h

@@ -8,11 +8,11 @@
 #define mozilla_dom_HTMLLinkElement_h
 
 #include "mozilla/Attributes.h"
+#include "mozilla/nsGenericHTMLElementWithFetchPriorityAttribute.h"
 #include "mozilla/dom/HTMLDNSPrefetch.h"
 #include "mozilla/dom/LinkStyle.h"
 #include "mozilla/dom/Link.h"
 #include "mozilla/WeakPtr.h"
-#include "nsGenericHTMLElement.h"
 #include "nsDOMTokenList.h"
 
 namespace mozilla {
@@ -22,9 +22,10 @@ class PreloaderBase;
 
 namespace dom {
 
-class HTMLLinkElement final : public nsGenericHTMLElement,
-                              public LinkStyle,
-                              public SupportsDNSPrefetch {
+class HTMLLinkElement final
+    : public nsGenericHTMLElementWithFetchPriorityAttribute,
+      public LinkStyle,
+      public SupportsDNSPrefetch {
  public:
   explicit HTMLLinkElement(
       already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo);

dom/webidl/HTMLLinkElement.webidl

@@ -11,7 +11,7 @@
  * and create derivative works of this document.
  */
 
-// http://www.whatwg.org/specs/web-apps/current-work/#the-link-element
+// https://html.spec.whatwg.org/multipage/semantics.html#the-link-element
 [Exposed=Window]
 interface HTMLLinkElement : HTMLElement {
   [HTMLConstructor] constructor();
@@ -39,10 +39,12 @@ interface HTMLLinkElement : HTMLElement {
            attribute USVString imageSrcset;
   [CEReactions, SetterThrows, Pure]
            attribute USVString imageSizes;
+  [Pref="network.fetchpriority.enabled", CEReactions]
+           attribute DOMString fetchPriority;
 };
 HTMLLinkElement includes LinkStyle;
 
-// http://www.whatwg.org/specs/web-apps/current-work/#other-elements,-attributes-and-apis
+// https://html.spec.whatwg.org/multipage/obsolete.html#other-elements%2C-attributes-and-apis
 partial interface HTMLLinkElement {
   [CEReactions, SetterThrows, Pure]
            attribute DOMString charset;
@@ -52,13 +54,13 @@ partial interface HTMLLinkElement {
            attribute DOMString target;
 };
 
-// https://w3c.github.io/webappsec/specs/subresourceintegrity/#htmllinkelement-1
+// https://html.spec.whatwg.org/multipage/semantics.html#the-link-element
 partial interface HTMLLinkElement {
   [CEReactions, SetterThrows]
   attribute DOMString integrity;
 };
 
-//https://w3c.github.io/preload/
+// https://html.spec.whatwg.org/multipage/links.html#link-type-preload
 partial interface HTMLLinkElement {
   [SetterThrows, Pure]
            attribute DOMString as;

testing/web-platform/meta/html/semantics/the-link-element/attr-link-fetchpriority.html.ini

@@ -1,6 +1,2 @@
 [attr-link-fetchpriority.html]
-  [fetchpriority attribute on <link> elements should reflect valid IDL values]
-    expected: FAIL
-
-  [default fetchpriority attribute on <link> elements should be 'auto']
-    expected: FAIL
+  prefs: [network.fetchpriority.enabled:true]