LibWeb: Add Document.getSelection

Userland/Libraries/LibWeb/DOM/Document.idl

@@ -18,6 +18,7 @@
 #import <HTML/HTMLElement.idl>
 #import <HTML/HTMLHeadElement.idl>
 #import <HTML/HTMLScriptElement.idl>
+#import <Selection/Selection.idl>
 
 // https://dom.spec.whatwg.org/#document
 [Exposed=Window]
@@ -103,6 +104,8 @@ interface Document : Node {
 
     [NewObject] NodeIterator createNodeIterator(Node root, optional unsigned long whatToShow = 0xFFFFFFFF, optional NodeFilter? filter = null);
     [NewObject] TreeWalker createTreeWalker(Node root, optional unsigned long whatToShow = 0xFFFFFFFF, optional NodeFilter? filter = null);
+
+    Selection? getSelection();
 };
 
 Document includes ParentNode;