chore: do not remove CSS in dev pages, fix icon page (#10159)

Author: jouni

dev/icon.html

@@ -6,11 +6,11 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Icon</title>
     <script type="module" src="./common.js"></script>
+    <link rel="stylesheet" href="../packages/vaadin-lumo-styles/src/props/icons.css">
 
     <script type="module">
       import '@vaadin/icon';
       import '@vaadin/icons/vaadin-iconset.js';
-      import '@vaadin/vaadin-lumo-styles/font-icons.js';
       import '@vaadin/tooltip';
       import { Iconset } from '@vaadin/icon/vaadin-iconset.js';
 

web-dev-server.config.js

@@ -54,11 +54,6 @@ export function enforceThemePlugin(theme) {
         body = body.replace('</title>', '</title><link rel="stylesheet" href="/packages/aura/aura.css" />');
       }
 
-      if (theme === 'base' && context.response.is('html', 'js')) {
-        // Remove all not transformed CSS imports
-        body = body.replaceAll(/^.+(vaadin-lumo-styles|\.\.)\/.+\.css.+$/gmu, '');
-      }
-
       return body;
     },
   };