LibWeb: Allocate AnimationFrameCallbackDriver on the JS heap

This avoids needing to creating root handles for each heap-allocated
object captured in the animation callback. An upcoming commit would add
several of these.

Userland/Libraries/LibWeb/HTML/AnimationFrameCallbackDriver.cpp

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2022, the SerenityOS developers.
+ * Copyright (c) 2024, Andreas Kling <andreas@ladybird.org>
+ * Copyright (c) 2024, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/HTML/AnimationFrameCallbackDriver.h>
+
+namespace Web::HTML {
+
+JS_DEFINE_ALLOCATOR(AnimationFrameCallbackDriver);
+
+void AnimationFrameCallbackDriver::visit_edges(Cell::Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_callbacks);
+}
+
+WebIDL::UnsignedLong AnimationFrameCallbackDriver::add(Callback handler)
+{
+    auto id = ++m_animation_frame_callback_identifier;
+    m_callbacks.set(id, handler);
+    return id;
+}
+
+bool AnimationFrameCallbackDriver::remove(WebIDL::UnsignedLong id)
+{
+    return m_callbacks.remove(id);
+}
+
+bool AnimationFrameCallbackDriver::has_callbacks() const
+{
+    return !m_callbacks.is_empty();
+}
+
+void AnimationFrameCallbackDriver::run(double now)
+{
+    auto taken_callbacks = move(m_callbacks);
+    for (auto& [id, callback] : taken_callbacks)
+        callback->function()(now);
+}
+
+}