Revert "LibWeb: Make "assign slottables for a tree" fast when there are no slots"

This reverts commit adc25af8e2.

This caused images to stop loading on https://reddit.com/ and needs
more investigation.

Libraries/LibWeb/DOM/ShadowRoot.h

@@ -64,20 +64,6 @@ public:
 
     virtual void finalize() override;
 
-    void increment_slot_count() { ++m_slot_count; }
-    void decrement_slot_count() { --m_slot_count; }
-    [[nodiscard]] size_t slot_count() const { return m_slot_count; }
-
-    template<typename Callback>
-    void for_each_slot(Callback callback)
-    {
-        if (m_slot_count == 0)
-            return;
-        for_each_in_subtree_of_type<HTML::HTMLSlotElement>([&](HTML::HTMLSlotElement& slot) {
-            return callback(slot);
-        });
-    }
-
 protected:
     virtual void visit_edges(Cell::Visitor&) override;
 
@@ -106,9 +92,6 @@ private:
 
     GC::Ptr<CSS::StyleSheetList> m_style_sheets;
     mutable GC::Ptr<WebIDL::ObservableArray> m_adopted_style_sheets;
-
-    // AD-HOC: Number of HTMLSlotElement nodes that are descendants of this ShadowRoot.
-    size_t m_slot_count { 0 };
 };
 
 template<>

Libraries/LibWeb/DOM/Slottable.cpp

@@ -74,32 +74,32 @@ GC::Ptr<HTML::HTMLSlotElement> find_a_slot(Slottable const& slottable, OpenFlag
     // 5. If shadow’s slot assignment is "manual", then return the slot in shadow’s descendants whose manually assigned
     //    nodes contains slottable, if any; otherwise null.
     if (shadow->slot_assignment() == Bindings::SlotAssignmentMode::Manual) {
-        GC::Ptr<HTML::HTMLSlotElement> found_slot;
+        GC::Ptr<HTML::HTMLSlotElement> slot;
 
-        shadow->for_each_slot([&](auto& slot) {
-            if (!slot.manually_assigned_nodes().contains_slow(slottable))
+        shadow->for_each_in_subtree_of_type<HTML::HTMLSlotElement>([&](auto& child) {
+            if (!child.manually_assigned_nodes().contains_slow(slottable))
                 return TraversalDecision::Continue;
 
-            found_slot = slot;
+            slot = child;
             return TraversalDecision::Break;
         });
 
-        return found_slot;
+        return slot;
     }
 
     // 6. Return the first slot in tree order in shadow’s descendants whose name is slottable’s name, if any; otherwise null.
     auto const& slottable_name = slottable.visit([](auto const& node) { return node->slottable_name(); });
-    GC::Ptr<HTML::HTMLSlotElement> found_slot;
+    GC::Ptr<HTML::HTMLSlotElement> slot;
 
-    shadow->for_each_slot([&](auto& slot) {
-        if (slot.slot_name() != slottable_name)
+    shadow->for_each_in_subtree_of_type<HTML::HTMLSlotElement>([&](auto& child) {
+        if (child.slot_name() != slottable_name)
             return TraversalDecision::Continue;
 
-        found_slot = slot;
+        slot = child;
         return TraversalDecision::Break;
     });
 
-    return found_slot;
+    return slot;
 }
 
 // https://dom.spec.whatwg.org/#find-slotables
@@ -186,7 +186,7 @@ void assign_slottables_for_a_tree(GC::Ref<Node> root)
 
     // To assign slottables for a tree, given a node root, run assign slottables for each slot slot in root’s inclusive
     // descendants, in tree order.
-    static_cast<DOM::ShadowRoot&>(*root).for_each_slot([](auto& slot) {
+    root->for_each_in_inclusive_subtree_of_type<HTML::HTMLSlotElement>([](auto& slot) {
         assign_slottables(slot);
         return TraversalDecision::Continue;
     });

Libraries/LibWeb/HTML/HTMLSlotElement.cpp

@@ -8,7 +8,6 @@
 #include <LibWeb/Bindings/HTMLSlotElementPrototype.h>
 #include <LibWeb/Bindings/Intrinsics.h>
 #include <LibWeb/DOM/Element.h>
-#include <LibWeb/DOM/ShadowRoot.h>
 #include <LibWeb/DOM/Text.h>
 #include <LibWeb/HTML/HTMLSlotElement.h>
 
@@ -148,21 +147,4 @@ void HTMLSlotElement::attribute_changed(FlyString const& local_name, Optional<St
     }
 }
 
-void HTMLSlotElement::inserted()
-{
-    Base::inserted();
-    auto& root = this->root();
-    if (!root.is_shadow_root())
-        return;
-    static_cast<DOM::ShadowRoot&>(root).increment_slot_count();
-}
-
-void HTMLSlotElement::removed_from(Node* old_parent, Node& old_root)
-{
-    Base::removed_from(old_parent, old_root);
-    if (!old_root.is_shadow_root())
-        return;
-    static_cast<DOM::ShadowRoot&>(old_root).decrement_slot_count();
-}
-
 }

Libraries/LibWeb/HTML/HTMLSlotElement.h

@@ -45,9 +45,6 @@ private:
     virtual void initialize(JS::Realm&) override;
     virtual void visit_edges(JS::Cell::Visitor&) override;
 
-    virtual void inserted() override;
-    virtual void removed_from(Node* old_parent, Node& old_root) override;
-
     virtual void attribute_changed(FlyString const& name, Optional<String> const& old_value, Optional<String> const& value, Optional<FlyString> const& namespace_) override;
 
     // https://html.spec.whatwg.org/multipage/scripting.html#manually-assigned-nodes