LibHTML: Start fleshing out a basic layout tree.

LibHTML/LayoutNode.cpp

@@ -0,0 +1,33 @@
+#include <LibHTML/LayoutNode.h>
+
+LayoutNode::LayoutNode(const Node* node)
+    : m_node(node)
+{
+}
+
+LayoutNode::~LayoutNode()
+{
+}
+
+void LayoutNode::retain()
+{
+    ASSERT(m_retain_count);
+    ++m_retain_count;
+}
+
+void LayoutNode::release()
+{
+    ASSERT(m_retain_count);
+    if (!--m_retain_count)
+        delete this;
+}
+
+void LayoutNode::append_child(Retained<LayoutNode> node)
+{
+    if (m_last_child)
+        m_last_child->set_next_sibling(node.ptr());
+    node->m_parent_node = this;
+    m_last_child = &node.leak_ref();
+    if (!m_first_child)
+        m_first_child = m_last_child;
+}