LibWeb: Add non-const variants of Document::{html_element,body,head}()

Userland/Libraries/LibWeb/DOM/Document.cpp

@@ -184,7 +184,7 @@ const Element* Document::document_element() const
     return first_child_of_type<Element>();
 }
 
-const HTML::HTMLHtmlElement* Document::html_element() const
+HTML::HTMLHtmlElement* Document::html_element()
 {
     auto* html = document_element();
     if (is<HTML::HTMLHtmlElement>(html))
@@ -192,7 +192,7 @@ const HTML::HTMLHtmlElement* Document::html_element() const
     return nullptr;
 }
 
-const HTML::HTMLHeadElement* Document::head() const
+HTML::HTMLHeadElement* Document::head()
 {
     auto* html = html_element();
     if (!html)
@@ -200,7 +200,7 @@ const HTML::HTMLHeadElement* Document::head() const
     return html->first_child_of_type<HTML::HTMLHeadElement>();
 }
 
-const HTML::HTMLElement* Document::body() const
+HTML::HTMLElement* Document::body()
 {
     auto* html = html_element();
     if (!html)

Userland/Libraries/LibWeb/DOM/Document.h

@@ -91,9 +91,25 @@ public:
     Element* document_element();
     const Element* document_element() const;
 
-    const HTML::HTMLHtmlElement* html_element() const;
-    const HTML::HTMLHeadElement* head() const;
-    const HTML::HTMLElement* body() const;
+    HTML::HTMLHtmlElement* html_element();
+    HTML::HTMLHeadElement* head();
+    HTML::HTMLElement* body();
+
+    const HTML::HTMLHtmlElement* html_element() const
+    {
+        return const_cast<Document*>(this)->html_element();
+    }
+
+    const HTML::HTMLHeadElement* head() const
+    {
+        return const_cast<Document*>(this)->head();
+    }
+
+    const HTML::HTMLElement* body() const
+    {
+        return const_cast<Document*>(this)->body();
+    }
+
     ExceptionOr<void> set_body(HTML::HTMLElement& new_body);
 
     String title() const;