Document render-blocking with <link rel=expect>

https://bugs.webkit.org/show_bug.cgi?id=268743
<rdar://122797243>

Reviewed by Tim Nguyen.

Implements the render-blocking concept on Document, and the rel=expect attribute for <link>.
https://html.spec.whatwg.org/multipage/dom.html#block-rendering

utils.js changed to generate a unique URL for each parser delay, otherwise we
cache the loads (which may not be spec compliant, but unrelated to
render-blocking).

Render blocking uses the existing code addVisualUpdatePreventedReason to prevent rendering, and rAF.

Some of the test fail because they have no render blocking (since an attempt was
rejected due to a mismatched media query or similar). These tests expect
rendering to happen mid-parsing, but don't due to our existing layer tree
freezing code. I've opted not to change the existing behaviour for now, and only
have this kick in when there is explicit (and active) render blocking elements.

As an optimization, when an <a> element changes, we pass that element into the 'process internal
resource links' algorithm. Rather than doing a tree search for each link looking for matching anchors,
we can just directly check if the link matches the mutated <a>.

* LayoutTests/TestExpectations:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-002-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-004-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-005-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-007-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-009-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-010-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-013-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-014-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-015-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-016-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-017-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-018-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-019-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-020-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-021-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-022-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-023-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-025-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-026-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-028-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-029-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-030-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-031-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-032-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-034-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-035-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-036-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-037-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-038-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/remove-element-unblocks-rendering.optional-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/support/utils.js:
(generateParserDelay):
* LayoutTests/imported/w3c/web-platform-tests/loading/resources/dummy.js: Added.
* LayoutTests/platform/glib/TestExpectations:
* Source/WebCore/dom/Document.cpp:
(WebCore::Document::setReadyState):
(WebCore::Document::setVisualUpdatesAllowed):
(WebCore::Document::addVisualUpdatePreventedReason):
(WebCore::Document::removeVisualUpdatePreventedReason):
(WebCore::Document::visualUpdatesSuppressionTimerFired):
(WebCore::Document::setVisualUpdatesAllowedByClient):
(WebCore::Document::suspend):
(WebCore::Document::resume):
(WebCore::Document::allowsAddingRenderBlockedElements const):
(WebCore::Document::isRenderBlocked const):
(WebCore::Document::blockRenderingOn):
(WebCore::Document::unblockRenderingOn):
(WebCore::Document::processInternalResourceLinks):
* Source/WebCore/dom/Document.h:
(WebCore::Document::visualUpdatesAllowed const):
* Source/WebCore/html/HTMLAnchorElement.cpp:
(WebCore::HTMLAnchorElement::attributeChanged):
(WebCore::HTMLAnchorElement::insertedIntoAncestor):
* Source/WebCore/html/HTMLAnchorElement.h:
* Source/WebCore/html/HTMLAttributeNames.in:
* Source/WebCore/html/HTMLLinkElement.cpp:
(WebCore::ExpectIdTargetObserver::ExpectIdTargetObserver):
(WebCore::ExpectIdTargetObserver::idTargetChanged):
(WebCore::HTMLLinkElement::attributeChanged):
(WebCore::HTMLLinkElement::process):
(WebCore::HTMLLinkElement::processInternalResourceLink):
(WebCore::HTMLLinkElement::unblockRendering):
(WebCore::HTMLLinkElement::removedFromAncestor):
(WebCore::HTMLLinkElement::blocking):
* Source/WebCore/html/HTMLLinkElement.h:
* Source/WebCore/html/HTMLLinkElement.idl:
* Source/WebCore/html/LinkRelAttribute.cpp:
(WebCore::LinkRelAttribute::LinkRelAttribute):
* Source/WebCore/html/LinkRelAttribute.h:

Canonical link: https://commits.webkit.org/282279@main

LayoutTests/TestExpectations

@@ -6904,6 +6904,17 @@ imported/w3c/web-platform-tests/webcodecs/videoFrame-createImageBitmap.https.any
 imported/w3c/web-platform-tests/webcodecs/video-encoder.https.any.worker.html [ DumpJSConsoleLogInStdErr ]
 imported/w3c/web-platform-tests/webcodecs/video-encoder.https.any.html [ DumpJSConsoleLogInStdErr ]
 
+# These tests don't actually have render blocking (due to adding the blocking too late, or non-matching
+# media queries etc). They expect the test to render midway through parsing, but our existing layer tree
+# freezing prevents that. These tests fail intentionally, unless we decide to change our existing heuristics.
+imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-007.html [ Failure ]
+imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-014.html [ Failure ]
+imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-017.html [ Failure ]
+imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-018.html [ Failure ]
+imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-021.html [ Failure ]
+imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-022.html [ Failure ]
+imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-036.html [ Failure ]
+
 # AudioDecoder, AudioEncoder and AudioData implementations missing.
 imported/w3c/web-platform-tests/webcodecs/audio-decoder.crossOriginIsolated.https.any.html [ Failure ]
 imported/w3c/web-platform-tests/webcodecs/audio-decoder.crossOriginIsolated.https.any.worker.html [ Failure ]

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/blocking-idl-attr-expected.txt

@@ -1,6 +1,6 @@
 
-FAIL Supported tokens of the 'blocking' IDL attribute of the link element undefined is not an object (evaluating 'link.blocking.supports')
-FAIL Setting the 'blocking' IDL attribute of the link element assert_equals: expected (string) "asdf" but got (undefined) undefined
+PASS Supported tokens of the 'blocking' IDL attribute of the link element
+PASS Setting the 'blocking' IDL attribute of the link element
 FAIL Supported tokens of the 'blocking' IDL attribute of the script element undefined is not an object (evaluating 'script.blocking.supports')
 FAIL Setting the 'blocking' IDL attribute of the script element assert_equals: expected (string) "asdf" but got (undefined) undefined
 FAIL Supported tokens of the 'blocking' IDL attribute of the style element undefined is not an object (evaluating 'style.blocking.supports')

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-002-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL blocking defers until needed element is parsed assert_false: expected false got true
+PASS blocking defers until needed element is parsed
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-004-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL removing link in the head makes it no longer blocking assert_false: expected false got true
+PASS removing link in the head makes it no longer blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-005-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL removing 'blocking' makes it no longer blocking assert_false: expected false got true
+PASS removing 'blocking' makes it no longer blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-007-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL link with non-matching media has no effect assert_false: expected false got true
+PASS link with non-matching media has no effect
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-009-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL changing media to non-matching makes it non blocking assert_false: expected false got true
+PASS changing media to non-matching makes it non blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-010-expected.txt

@@ -1,4 +1,4 @@
 CONSOLE MESSAGE: Did not parse stylesheet at 'http://localhost:8800/html/dom/render-blocking/element-render-blocking-010.html' because non CSS MIME types are not allowed in strict mode.
 
-FAIL changing rel to non-expect makes it non blocking assert_false: expected false got true
+PASS changing rel to non-expect makes it non blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-013-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL removing href makes it no longer blocking assert_false: expected false got true
+PASS removing href makes it no longer blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-014-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL link in the body has no effect assert_false: expected false got true
+PASS link in the body has no effect
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-015-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL removing link the body makes it non blocking assert_false: expected false got true
+PASS removing link the body makes it non blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-016-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL removing 'blocking' in the body makes it non blocking assert_false: expected false got true
+PASS removing 'blocking' in the body makes it non blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-017-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL adding 'blocking=render' in the body has no effect assert_false: expected false got true
+PASS adding 'blocking=render' in the body has no effect
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-018-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL changing media to matching in the body has no effect assert_false: expected false got true
+PASS changing media to matching in the body has no effect
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-019-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL changing media to non-matching in the body makes it non blocking assert_false: expected false got true
+PASS changing media to non-matching in the body makes it non blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-020-expected.txt

@@ -1,4 +1,4 @@
 CONSOLE MESSAGE: Did not parse stylesheet at 'http://localhost:8800/html/dom/render-blocking/element-render-blocking-020.html' because non CSS MIME types are not allowed in strict mode.
 
-FAIL changing rel to non-expect in the body makes it non blocking assert_false: expected false got true
+PASS changing rel to non-expect in the body makes it non blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-021-expected.txt

@@ -1,4 +1,4 @@
 CONSOLE MESSAGE: Did not parse stylesheet at 'http://localhost:8800/html/dom/render-blocking/element-render-blocking-021.html' because non CSS MIME types are not allowed in strict mode.
 
-FAIL changing rel to expect in the body has no effect assert_false: expected false got true
+PASS changing rel to expect in the body has no effect
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-022-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL adding href in the body has no effect assert_false: expected false got true
+PASS adding href in the body has no effect
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-023-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL removing href in the body makes it non blocking assert_false: expected false got true
+PASS removing href in the body makes it non blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-025-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL adding an id in the body satisfies render block assert_false: expected false got true
+PASS adding an id in the body satisfies render block
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-026-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL removing id after it was renderer keeps render block satisfied assert_false: expected false got true
+PASS removing id after it was renderer keeps render block satisfied
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-028-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL removing some links but not all keeps at least the matching link blocking assert_false: expected false got true
+PASS removing some links but not all keeps at least the matching link blocking
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-029-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL blocking defers frames until full parsing assert_false: expected false got true
+PASS blocking defers frames until full parsing
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-030-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL blocking defers frames until full parsing assert_false: expected false got true
+PASS blocking defers frames until full parsing
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-031-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL blocking defers frames until full parsing assert_false: expected false got true
+PASS blocking defers frames until full parsing
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-032-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL blocking defers frames until full parsing assert_false: expected false got true
+PASS blocking defers frames until full parsing
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-034-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL relative URLs that match this document are OK assert_false: expected false got true
+PASS relative URLs that match this document are OK
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-035-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL relative URLs that match this document are OK, regarless of <base> assert_false: expected false got true
+PASS relative URLs that match this document are OK, regarless of <base>
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-036-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL link URLs are relative to base URL, not to document URL assert_false: expected false got true
+PASS link URLs are relative to base URL, not to document URL
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-037-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL relative URLs that match this document are OK, regarless of <base> assert_false: expected false got true
+PASS relative URLs that match this document are OK, regarless of <base>
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-038-expected.txt

@@ -1,3 +1,3 @@
 
-FAIL link rel=expect: only connected elements are eligible assert_false: The last element should not be there yet, even though it's created (in a shadow root) expected false got true
+PASS link rel=expect: only connected elements are eligible
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/remove-element-unblocks-rendering.optional-expected.txt

@@ -7,5 +7,5 @@ PASS Render-blocking on parser-inserted async module script is cancellable
 PASS Render-blocking on script-inserted stylesheet link is cancellable
 PASS Render-blocking on script-inserted script is cancellable
 PASS Render-blocking on script-inserted module script is cancellable
-PASS Render-blocking on script-inserted inline style is cancellable
+FAIL Render-blocking on script-inserted inline style is cancellable assert_false: expected false got true
 

LayoutTests/imported/w3c/web-platform-tests/html/dom/render-blocking/support/utils.js

@@ -1,4 +1,5 @@
 function generateParserDelay(seconds = 1) {
+  seconds += (Math.random() / 10.0);
   document.write(`
     <script src="/loading/resources/dummy.js?pipe=trickle(d${seconds})"></script>
   `);

LayoutTests/imported/w3c/web-platform-tests/loading/resources/dummy.js

@@ -0,0 +1 @@
+/* Nothing to see here */

LayoutTests/platform/glib/TestExpectations

@@ -4121,6 +4121,8 @@ imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking
 imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-011.html [ Failure ]
 imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-020.html [ Failure ]
 imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-021.html [ Failure ]
+imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-024.html [ Failure ]
+imported/w3c/web-platform-tests/html/dom/render-blocking/element-render-blocking-027.html [ Failure ]
 
 imported/w3c/web-platform-tests/html/browsers/browsing-the-web/read-media/pageload-video.html [ Failure ]
 

Source/WebCore/dom/Document.cpp

@@ -1917,6 +1917,7 @@ void Document::removeVisualUpdatePreventedReasons(OptionSet<VisualUpdatesPrevent
 
     if (RefPtr frame = this->frame())
         frame->checkedLoader()->completePageTransitionIfNeeded();
+    scheduleRenderingUpdate({ });
 }
 
 void Document::visualUpdatesSuppressionTimerFired()
@@ -8298,6 +8299,42 @@ void Document::clearScriptedAnimationController()
         scriptedAnimationController->clearDocumentPointer();
 }
 
+// https://html.spec.whatwg.org/multipage/dom.html#render-blocking-mechanism
+bool Document::allowsAddingRenderBlockedElements() const
+{
+    return contentType() == "text/html"_s && !body();
+}
+
+bool Document::isRenderBlocked() const
+{
+    return m_visualUpdatesPreventedReasons.contains(VisualUpdatesPreventedReason::RenderBlocking);
+}
+
+void Document::blockRenderingOn(Element& element)
+{
+    if (allowsAddingRenderBlockedElements()) {
+        m_renderBlockingElements.add(element);
+        addVisualUpdatePreventedReason(VisualUpdatesPreventedReason::RenderBlocking);
+    }
+}
+
+void Document::unblockRenderingOn(Element& element)
+{
+    m_renderBlockingElements.remove(element);
+    if (m_renderBlockingElements.isEmptyIgnoringNullReferences())
+        removeVisualUpdatePreventedReasons(VisualUpdatesPreventedReason::RenderBlocking);
+}
+
+// https://html.spec.whatwg.org/multipage/links.html#process-internal-resource-links
+void Document::processInternalResourceLinks(HTMLAnchorElement& anchor)
+{
+    auto copy = copyToVector(m_renderBlockingElements);
+    for (auto& element : copy) {
+        if (RefPtr link = dynamicDowncast<HTMLLinkElement>(element.get()))
+            link->processInternalResourceLink(&anchor);
+    }
+}
+
 CheckedRef<FrameSelection> Document::checkedSelection()
 {
     return m_selection.get();

Source/WebCore/dom/Document.h

@@ -145,6 +145,7 @@ class Frame;
 class GPUCanvasContext;
 class GraphicsClient;
 class HTMLAllCollection;
+class HTMLAnchorElement;
 class HTMLAttachmentElement;
 class HTMLBaseElement;
 class HTMLBodyElement;
@@ -1824,6 +1825,12 @@ class Document
     void updateServiceWorkerClientData() final;
     WEBCORE_EXPORT void navigateFromServiceWorker(const URL&, CompletionHandler<void(ScheduleLocationChangeResult)>&&);
 
+    bool allowsAddingRenderBlockedElements() const;
+    bool isRenderBlocked() const;
+    void blockRenderingOn(Element&);
+    void unblockRenderingOn(Element&);
+    void processInternalResourceLinks(HTMLAnchorElement&);
+
 #if ENABLE(VIDEO)
     WEBCORE_EXPORT void forEachMediaElement(const Function<void(HTMLMediaElement&)>&);
 #endif
@@ -2061,8 +2068,9 @@ class Document
         Client         = 1 << 0,
         ReadyState     = 1 << 1,
         Suspension     = 1 << 2,
+        RenderBlocking = 1 << 3,
     };
-    static constexpr OptionSet<VisualUpdatesPreventedReason> visualUpdatePreventReasonsClearedByTimer() { return { VisualUpdatesPreventedReason::ReadyState }; }
+    static constexpr OptionSet<VisualUpdatesPreventedReason> visualUpdatePreventReasonsClearedByTimer() { return { VisualUpdatesPreventedReason::ReadyState, VisualUpdatesPreventedReason::RenderBlocking }; }
     static constexpr OptionSet<VisualUpdatesPreventedReason> visualUpdatePreventRequiresLayoutMilestones() { return { VisualUpdatesPreventedReason::Client, VisualUpdatesPreventedReason::ReadyState }; }
 
     void addVisualUpdatePreventedReason(VisualUpdatesPreventedReason);
@@ -2452,6 +2460,8 @@ class Document
 
     WeakHashSet<Element, WeakPtrImplWithEventTargetData> m_elementsWithPendingUserAgentShadowTreeUpdates;
 
+    WeakHashSet<Element, WeakPtrImplWithEventTargetData> m_renderBlockingElements;
+
     RefPtr<ReportingScope> m_reportingScope;
 
     std::unique_ptr<WakeLockManager> m_wakeLockManager;

Source/WebCore/html/HTMLAnchorElement.cpp

@@ -260,7 +260,8 @@ void HTMLAnchorElement::attributeChanged(const QualifiedName& name, const AtomSt
             m_linkRelations.add(Relation::Opener);
         if (m_relList)
             m_relList->associatedAttributeValueChanged();
-    }
+    } else if (name == nameAttr)
+        document().processInternalResourceLinks(*this);
 }
 
 bool HTMLAnchorElement::isURLAttribute(const Attribute& attribute) const
@@ -746,4 +747,11 @@ ReferrerPolicy HTMLAnchorElement::referrerPolicy() const
     return parseReferrerPolicy(attributeWithoutSynchronization(referrerpolicyAttr), ReferrerPolicySource::ReferrerPolicyAttribute).value_or(ReferrerPolicy::EmptyString);
 }
 
+Node::InsertedIntoAncestorResult HTMLAnchorElement::insertedIntoAncestor(InsertionType insertionType, ContainerNode& parentOfInsertedTree)
+{
+    auto result = HTMLElement::insertedIntoAncestor(insertionType, parentOfInsertedTree);
+    document().processInternalResourceLinks(*this);
+    return result;
+}
+
 }

Source/WebCore/html/HTMLAnchorElement.h

@@ -83,6 +83,8 @@ class HTMLAnchorElement : public HTMLElement, public URLDecomposition {
     String referrerPolicyForBindings() const;
     ReferrerPolicy referrerPolicy() const;
 
+    Node::InsertedIntoAncestorResult insertedIntoAncestor(InsertionType, ContainerNode& parentOfInsertedTree) override;
+
 protected:
     HTMLAnchorElement(const QualifiedName&, Document&);
 

Source/WebCore/html/HTMLAttributeNames.in

@@ -83,6 +83,7 @@ axis
 background
 behavior
 bgcolor
+blocking
 border
 bordercolor
 capture