fill an empty @name with the default placeholder

fixes #462

edit/source-editor.js

@@ -110,12 +110,9 @@ function createSourceEditor(style) {
     }
     const DEFAULT_CODE = `
       /* ==UserStyle==
-      @name           ${
-        style.name ||
-        t('usercssReplaceTemplateName') + ' - ' + new Date().toLocaleString()
-      }
+      @name           ${''/* a trick to preserve the trailing spaces */}
       @namespace      github.com/openstyles/stylus
-      @version        0.1.0
+      @version        1.0.0
       @description    A new userstyle
       @author         Me
       ==/UserStyle== */
@@ -126,6 +123,10 @@ function createSourceEditor(style) {
 
     chromeSync.getLZValue('usercssTemplate').then(code => {
       code = code || DEFAULT_CODE;
+      code = code.replace(/@name(\s*)(?=[\r\n])/, (str, space) =>
+        `${str}${space ? '' : ' '}${
+          style.name ||
+          t('usercssReplaceTemplateName') + ' - ' + new Date().toLocaleString()}`);
       // strip the last dummy section if any, add an empty line followed by the section
       style.sourceCode = code.replace(/@-moz-document[^{]*\{[^}]*\}\s*$|\s+$/g, '') + '\n\n' + section;
       cm.startOperation();