Fix locale JS files not being added; add (temporary?) API to add locale CSS files

fixes flarum/core#970

framework/core/src/Event/ConfigureLocales.php

@@ -63,6 +63,10 @@ class ConfigureLocales
             $this->locales->addJsFile($locale, $file);
         }
 
+        if (file_exists($file = $localeDir.'/config.css')) {
+            $this->locales->addCssFile($locale, $file);
+        }
+
         foreach (new DirectoryIterator($localeDir) as $file) {
             if ($file->isFile() && in_array($file->getExtension(), ['yml', 'yaml'])) {
                 $this->locales->addTranslations($locale, $file->getPathname());

framework/core/src/Http/WebApp/WebAppView.php

@@ -159,6 +159,14 @@ class WebAppView
         $locale = $this->locales->getLocale();
         $this->localeJs = $this->assets->getLocaleJs($locale);
         $this->localeCss = $this->assets->getLocaleCss($locale);
+
+        foreach ($this->locales->getJsFiles($locale) as $file) {
+            $this->localeJs->addFile($file);
+        }
+
+        foreach ($this->locales->getCssFiles($locale) as $file) {
+            $this->localeCss->addFile($file);
+        }
     }
 
     /**

framework/core/src/Locale/LocaleManager.php

@@ -23,6 +23,8 @@ class LocaleManager
 
     protected $js = [];
 
+    protected $css = [];
+
     /**
      * @param SymfonyTranslator $translator
      */
@@ -79,6 +81,24 @@ class LocaleManager
         return $files;
     }
 
+    public function addCssFile($locale, $css)
+    {
+        $this->css[$locale][] = $css;
+    }
+
+    public function getCssFiles($locale)
+    {
+        $files = array_get($this->css, $locale, []);
+
+        $parts = explode('-', $locale);
+
+        if (count($parts) > 1) {
+            $files = array_merge(array_get($this->css, $parts[0], []), $files);
+        }
+
+        return $files;
+    }
+
     /**
      * @return SymfonyTranslator
      */