Fix Granite style class deprecations

Author: danirabbit

src/Views/Appearance.vala

@@ -450,8 +450,7 @@ public class PantheonShell.Appearance : Switchboard.SettingsPage {
             overlay.add_overlay (dock);
             overlay.add_overlay (window_back);
             overlay.add_overlay (window_front);
-            overlay.add_css_class (Granite.STYLE_CLASS_CARD);
-            overlay.add_css_class (Granite.STYLE_CLASS_ROUNDED);
+            overlay.add_css_class (Granite.CssClass.CARD);
 
             var monitor = Gdk.Display.get_default ().get_monitor_at_surface (
                 (((Gtk.Application) Application.get_default ()).active_window).get_surface ()

src/Views/Wallpaper.vala

@@ -113,9 +113,12 @@ public class PantheonShell.Wallpaper : Switchboard.SettingsPage {
         var box = new Gtk.Box (VERTICAL, 0);
         box.append (view_overlay);
         box.append (actionbar);
-        box.add_css_class (Granite.STYLE_CLASS_FRAME);
 
-        child = box;
+        var frame = new Gtk.Frame (null) {
+            child = box
+        };
+
+        child = frame;
         add_css_class ("wallpaper");
 
         add_wallpaper_button.clicked.connect (show_wallpaper_chooser);

src/Widgets/WallpaperContainer.vala

@@ -74,8 +74,7 @@ public class PantheonShell.WallpaperContainer : Gtk.FlowBoxChild {
             content_fit = COVER,
             height_request = THUMB_HEIGHT
         };
-        image.add_css_class (Granite.STYLE_CLASS_CARD);
-        image.add_css_class (Granite.STYLE_CLASS_ROUNDED);
+        image.add_css_class (Granite.CssClass.CARD);
 
         var check = new Gtk.CheckButton () {
             active = true,