LibWeb: Add imports to all IDL files that depend on others

Author: https://github.com/alimpfard
Commit: a59800b4a0
Pull-request: https://github.com/SerenityOS/serenity/pull/12548
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibWeb/DOM/DocumentFragment.idl

@@ -1,3 +1,8 @@
+#import <DOM/Element.idl>
+#import <DOM/HTMLCollection.idl>
+#import <DOM/Node.idl>
+#import <DOM/NodeList.idl>
+
 interface DocumentFragment : Node {
 
     constructor();