LibWeb: Begin implementing the Clipboard API

https://w3c.github.io/clipboard-apis/

This implements enough for navigator.clipboard.writeText(String).

Userland/Libraries/LibWeb/HTML/EventLoop/Task.h

@@ -47,6 +47,12 @@ public:
         // https://html.spec.whatwg.org/multipage/canvas.html#canvas-blob-serialisation-task-source
         CanvasBlobSerializationTask,
 
+        // https://w3c.github.io/clipboard-apis/#clipboard-task-source
+        Clipboard,
+
+        // https://w3c.github.io/permissions/#permissions-task-source
+        Permissions,
+
         // !!! IMPORTANT: Keep this field last!
         // This serves as the base value of all unique task sources.
         // Some elements, such as the HTMLMediaElement, must have a unique task source per instance.

Userland/Libraries/LibWeb/HTML/Navigator.cpp

@@ -8,6 +8,7 @@
 #include <LibJS/Heap/Heap.h>
 #include <LibJS/Runtime/Realm.h>
 #include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/Clipboard/Clipboard.h>
 #include <LibWeb/HTML/Navigator.h>
 #include <LibWeb/HTML/Scripting/Environments.h>
 #include <LibWeb/HTML/Window.h>
@@ -57,6 +58,7 @@ void Navigator::visit_edges(Cell::Visitor& visitor)
     Base::visit_edges(visitor);
     visitor.visit(m_mime_type_array);
     visitor.visit(m_plugin_array);
+    visitor.visit(m_clipboard);
 }
 
 JS::NonnullGCPtr<MimeTypeArray> Navigator::mime_types()
@@ -73,4 +75,11 @@ JS::NonnullGCPtr<PluginArray> Navigator::plugins()
     return *m_plugin_array;
 }
 
+JS::NonnullGCPtr<Clipboard::Clipboard> Navigator::clipboard()
+{
+    if (!m_clipboard)
+        m_clipboard = heap().allocate<Clipboard::Clipboard>(realm(), realm());
+    return *m_clipboard;
+}
+
 }

Userland/Libraries/LibWeb/HTML/Navigator.h

@@ -45,6 +45,7 @@ public:
 
     [[nodiscard]] JS::NonnullGCPtr<MimeTypeArray> mime_types();
     [[nodiscard]] JS::NonnullGCPtr<PluginArray> plugins();
+    [[nodiscard]] JS::NonnullGCPtr<Clipboard::Clipboard> clipboard();
 
     virtual ~Navigator() override;
 
@@ -58,6 +59,9 @@ private:
 
     JS::GCPtr<PluginArray> m_plugin_array;
     JS::GCPtr<MimeTypeArray> m_mime_type_array;
+
+    // https://w3c.github.io/clipboard-apis/#dom-navigator-clipboard
+    JS::GCPtr<Clipboard::Clipboard> m_clipboard;
 };
 
 }

Userland/Libraries/LibWeb/HTML/Navigator.idl

@@ -1,3 +1,4 @@
+#import <Clipboard/Clipboard.idl>
 #import <HTML/MimeTypeArray.idl>
 #import <HTML/NavigatorBeacon.idl>
 #import <HTML/NavigatorID.idl>
@@ -10,6 +11,9 @@
 [Exposed=Window]
 interface Navigator {
     // objects implementing this interface also implement the interfaces given below
+
+    // https://w3c.github.io/clipboard-apis/#navigator-interface
+    [SecureContext, SameObject] readonly attribute Clipboard clipboard;
 };
 
 // NOTE: As NavigatorContentUtils, NavigatorCookies, NavigatorPlugins, and NavigatorAutomationInformation