LibHTML: Add a simple <style> element for inline CSS

Libraries/LibHTML/DOM/HTMLStyleElement.cpp

@@ -0,0 +1,28 @@
+#include <LibHTML/DOM/Document.h>
+#include <LibHTML/DOM/HTMLStyleElement.h>
+#include <LibHTML/Parser/CSSParser.h>
+
+HTMLStyleElement::HTMLStyleElement(Document& document, const String& tag_name)
+    : HTMLElement(document, tag_name)
+{
+}
+
+HTMLStyleElement::~HTMLStyleElement()
+{
+}
+
+void HTMLStyleElement::inserted_into(Node& new_parent)
+{
+    m_stylesheet = parse_css(text_content());
+    if (m_stylesheet)
+        document().add_sheet(*m_stylesheet);
+    HTMLElement::inserted_into(new_parent);
+}
+
+void HTMLStyleElement::removed_from(Node& old_parent)
+{
+    if (m_stylesheet) {
+        // FIXME: Remove the sheet from the document
+    }
+    return HTMLElement::removed_from(old_parent);
+}

Libraries/LibHTML/DOM/HTMLStyleElement.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <LibHTML/DOM/HTMLElement.h>
+
+class StyleSheet;
+
+class HTMLStyleElement : public HTMLElement {
+public:
+    HTMLStyleElement(Document&, const String& tag_name);
+    virtual ~HTMLStyleElement() override;
+
+    virtual void inserted_into(Node&) override;
+    virtual void removed_from(Node&) override;
+
+private:
+    RefPtr<StyleSheet> m_stylesheet;
+};