LibWeb: Use invalidation sets to reduce style recalculation

Implements idea described in
https://docs.google.com/document/d/1vEW86DaeVs4uQzNFI5R-_xS9TcS1Cs_EUsHRSgCHGu8

Invalidation sets are used to reduce the number of elements marked for
style recalculation by collecting metadata from style rules about the
dependencies between properties that could affect an element’s style.

Currently, this optimization is only applied to style invalidation
triggered by class list mutations on an element.

Libraries/LibWeb/DOM/Node.cpp

@@ -470,6 +470,64 @@ void Node::invalidate_style(StyleInvalidationReason reason)
     document().schedule_style_update();
 }
 
+void Node::invalidate_style(StyleInvalidationReason reason, Vector<CSS::InvalidationSet::Property> const& properties)
+{
+    if (is_character_data())
+        return;
+
+    bool properties_used_in_has_selectors = false;
+    for (auto const& property : properties) {
+        properties_used_in_has_selectors |= document().style_computer().invalidation_property_used_in_has_selector(property);
+    }
+    if (properties_used_in_has_selectors) {
+        document().invalidate_style(reason);
+        return;
+    }
+
+    auto invalidation_set = document().style_computer().invalidation_set_for_properties(properties);
+    if (invalidation_set.is_empty())
+        return;
+
+    if (invalidation_set.needs_invalidate_self()) {
+        set_needs_style_update(true);
+    }
+
+    auto element_has_properties_from_invalidation_set = [&](Element& element) {
+        bool result = false;
+        invalidation_set.for_each_property([&](auto const& property) {
+            if (element.affected_by_invalidation_property(property))
+                result = true;
+        });
+        return result;
+    };
+
+    auto invalidate_entire_subtree = [&](Node& subtree_root) {
+        subtree_root.for_each_shadow_including_inclusive_descendant([&](Node& node) {
+            if (!node.is_element())
+                return TraversalDecision::Continue;
+            auto& element = static_cast<Element&>(node);
+            bool needs_style_recalculation = invalidation_set.needs_invalidate_whole_subtree() || element_has_properties_from_invalidation_set(element);
+            if (needs_style_recalculation) {
+                element.set_needs_style_update(true);
+            } else {
+                element.set_needs_inherited_style_update(true);
+            }
+            return TraversalDecision::Continue;
+        });
+    };
+
+    invalidate_entire_subtree(*this);
+
+    if (invalidation_set.needs_invalidate_whole_subtree()) {
+        for (auto* sibling = next_sibling(); sibling; sibling = sibling->next_sibling()) {
+            if (sibling->is_element())
+                invalidate_entire_subtree(*sibling);
+        }
+    }
+
+    document().schedule_style_update();
+}
+
 String Node::child_text_content() const
 {
     if (!is<ParentNode>(*this))