Libraries: Create top level directory for libraries.

Things were getting a little crowded in the project root, so this patch
moves the Lib*/ directories into Libraries/.

Libraries/LibHTML/DOM/Element.cpp

@@ -0,0 +1,64 @@
+#include <LibHTML/DOM/Element.h>
+#include <LibHTML/Layout/LayoutBlock.h>
+#include <LibHTML/Layout/LayoutInline.h>
+
+Element::Element(const String& tag_name)
+    : ParentNode(NodeType::ELEMENT_NODE)
+    , m_tag_name(tag_name)
+{
+}
+
+Element::~Element()
+{
+}
+
+Attribute* Element::find_attribute(const String& name)
+{
+    for (auto& attribute : m_attributes) {
+        if (attribute.name() == name)
+            return &attribute;
+    }
+    return nullptr;
+}
+
+const Attribute* Element::find_attribute(const String& name) const
+{
+    for (auto& attribute : m_attributes) {
+        if (attribute.name() == name)
+            return &attribute;
+    }
+    return nullptr;
+}
+
+String Element::attribute(const String& name) const
+{
+    if (auto* attribute = find_attribute(name))
+        return attribute->value();
+    return { };
+}
+
+void Element::set_attribute(const String& name, const String& value)
+{
+    if (auto* attribute = find_attribute(name))
+        attribute->set_value(value);
+    else
+        m_attributes.append({ name, value });
+}
+
+void Element::set_attributes(Vector<Attribute>&& attributes)
+{
+    m_attributes = move(attributes);
+}
+
+bool Element::has_class(const StringView& class_name) const
+{
+    auto value = attribute("class");
+    if (value.is_empty())
+        return false;
+    auto parts = value.split_view(' ');
+    for (auto& part : parts) {
+        if (part == class_name)
+            return true;
+    }
+    return false;
+}