LibWeb: Store all timelines associated with a document on the document

This will be required for propagating the current animation time to all
relevant timelines, which each propagate that time to all of their
relevant animations.

Userland/Libraries/LibWeb/Animations/AnimationTimeline.cpp

@@ -26,6 +26,10 @@ WebIDL::ExceptionOr<void> AnimationTimeline::set_current_time(Optional<double> v
 
 void AnimationTimeline::set_associated_document(JS::GCPtr<DOM::Document> document)
 {
+    if (document)
+        document->associate_with_timeline(*this);
+    if (m_associated_document)
+        m_associated_document->disassociate_with_timeline(*this);
     m_associated_document = document;
 }
 
@@ -41,6 +45,12 @@ AnimationTimeline::AnimationTimeline(JS::Realm& realm)
 {
 }
 
+AnimationTimeline::~AnimationTimeline()
+{
+    if (m_associated_document)
+        m_associated_document->disassociate_with_timeline(*this);
+}
+
 void AnimationTimeline::initialize(JS::Realm& realm)
 {
     Base::initialize(realm);

Userland/Libraries/LibWeb/Animations/AnimationTimeline.h

@@ -30,6 +30,7 @@ public:
 
 protected:
     AnimationTimeline(JS::Realm&);
+    virtual ~AnimationTimeline() override;
 
     virtual void initialize(JS::Realm&) override;
     virtual void visit_edges(Cell::Visitor&) override;

Userland/Libraries/LibWeb/Animations/DocumentTimeline.h

@@ -33,6 +33,7 @@ public:
 
 private:
     DocumentTimeline(JS::Realm&, DOM::Document&, HighResolutionTime::DOMHighResTimeStamp origin_time);
+    virtual ~DocumentTimeline() override = default;
 
     virtual void initialize(JS::Realm&) override;
 

Userland/Libraries/LibWeb/DOM/Document.cpp

@@ -404,6 +404,9 @@ void Document::visit_edges(Cell::Visitor& visitor)
 
     for (auto& observer : m_intersection_observers)
         visitor.visit(observer);
+
+    for (auto& timeline : m_associated_animation_timelines)
+        visitor.visit(timeline);
 }
 
 // https://w3c.github.io/selection-api/#dom-document-getselection
@@ -3572,4 +3575,14 @@ JS::NonnullGCPtr<Animations::DocumentTimeline> Document::timeline()
     return *m_default_timeline;
 }
 
+void Document::associate_with_timeline(JS::NonnullGCPtr<Animations::AnimationTimeline> timeline)
+{
+    m_associated_animation_timelines.set(timeline);
+}
+
+void Document::disassociate_with_timeline(JS::NonnullGCPtr<Animations::AnimationTimeline> timeline)
+{
+    m_associated_animation_timelines.remove(timeline);
+}
+
 }

Userland/Libraries/LibWeb/DOM/Document.h

@@ -536,6 +536,9 @@ public:
 
     JS::NonnullGCPtr<Animations::DocumentTimeline> timeline();
 
+    void associate_with_timeline(JS::NonnullGCPtr<Animations::AnimationTimeline>);
+    void disassociate_with_timeline(JS::NonnullGCPtr<Animations::AnimationTimeline>);
+
 protected:
     virtual void initialize(JS::Realm&) override;
     virtual void visit_edges(Cell::Visitor&) override;
@@ -743,6 +746,9 @@ private:
 
     HashMap<AK::URL, HTML::SharedImageRequest*> m_shared_image_requests;
 
+    // https://www.w3.org/TR/web-animations-1/#timeline-associated-with-a-document
+    HashTable<JS::NonnullGCPtr<Animations::AnimationTimeline>> m_associated_animation_timelines;
+
     // https://www.w3.org/TR/web-animations-1/#document-default-document-timeline
     JS::GCPtr<Animations::DocumentTimeline> m_default_timeline;
 };