Base+PixelPaint: Use Merge Active Layer Up/Down Icons

The icons for these actions were added in a previous commit but never
used, now they are.

Userland/Applications/PixelPaint/IconBag.cpp

@@ -36,6 +36,8 @@ ErrorOr<IconBag> IconBag::try_create()
     icon_bag.active_layer_down = TRY(Gfx::Bitmap::try_load_from_file("/res/icons/pixelpaint/active-layer-down.png"));
     icon_bag.delete_layer = TRY(Gfx::Bitmap::try_load_from_file("/res/icons/16x16/delete.png"));
     icon_bag.merge_visible = TRY(Gfx::Bitmap::try_load_from_file("/res/icons/pixelpaint/merge-visible.png"));
+    icon_bag.merge_active_layer_up = TRY(Gfx::Bitmap::try_load_from_file("/res/icons/pixelpaint/merge-active-layer-up.png"));
+    icon_bag.merge_active_layer_down = TRY(Gfx::Bitmap::try_load_from_file("/res/icons/pixelpaint/merge-active-layer-down.png"));
     icon_bag.filter = TRY(Gfx::Bitmap::try_load_from_file("/res/icons/pixelpaint/filter.png"));
 
     return icon_bag;

Userland/Applications/PixelPaint/IconBag.h

@@ -37,6 +37,8 @@ struct IconBag final {
     RefPtr<Gfx::Bitmap> active_layer_down { nullptr };
     RefPtr<Gfx::Bitmap> delete_layer { nullptr };
     RefPtr<Gfx::Bitmap> merge_visible { nullptr };
+    RefPtr<Gfx::Bitmap> merge_active_layer_up { nullptr };
+    RefPtr<Gfx::Bitmap> merge_active_layer_down { nullptr };
     RefPtr<Gfx::Bitmap> filter { nullptr };
 };
 }

Userland/Applications/PixelPaint/MainWidget.cpp

@@ -592,7 +592,7 @@ void MainWidget::initialize_menubar(GUI::Window& window)
         }));
 
     m_layer_menu->add_action(GUI::Action::create(
-        "Merge &Active Layer Up", [&](auto&) {
+        "Merge &Active Layer Up", g_icon_bag.merge_active_layer_up, [&](auto&) {
             auto* editor = current_image_editor();
             VERIFY(editor);
             auto active_layer = editor->active_layer();
@@ -603,7 +603,7 @@ void MainWidget::initialize_menubar(GUI::Window& window)
         }));
 
     m_layer_menu->add_action(GUI::Action::create(
-        "M&erge Active Layer Down", { Mod_Ctrl, Key_E }, [&](auto&) {
+        "M&erge Active Layer Down", { Mod_Ctrl, Key_E }, g_icon_bag.merge_active_layer_down, [&](auto&) {
             auto* editor = current_image_editor();
             VERIFY(editor);
             auto active_layer = editor->active_layer();