Group all Glass Stage dependencies under the selected layout

frontend/shell-consistency.test.js

@@ -49,3 +49,11 @@ test('assets.json describes the complete existing shell exactly once with eager
     for (const asset of groups[`feature:${name}`].embeddedIn) assert.ok(groups.core.files.includes(asset), `${name} remains in core`);
   }
 });
+
+test('the selected glass-stage layout includes its controls and panel dependencies', () => {
+  const { groups } = JSON.parse(readFileSync(join(__dirname, 'assets.json'), 'utf8'));
+  assert.deepEqual(groups['layout:glass-stage'].files, [
+    '/theme-glass.css', '/theme-glass-controls.css', '/glass-controls.js',
+    '/theme-glass-panel.css', '/glass-panel-layout.js',
+  ]);
+});