Add db_mut method to FontSystem

src/font/system/no_std.rs

@@ -43,6 +43,10 @@ impl FontSystem {
         &self.db
     }
 
+    pub fn db_mut(&mut self) -> &mut fontdb::Database {
+        &mut self.db
+    }
+
     pub fn get_font(&self, id: fontdb::ID) -> Option<Arc<Font>> {
         get_font(&self.db, id)
     }

src/font/system/std.rs

@@ -98,6 +98,11 @@ impl FontSystem {
         &self.db
     }
 
+    pub fn db_mut(&mut self) -> &mut fontdb::Database {
+        self.font_matches_cache.clear();
+        &mut self.db
+    }
+
     pub fn into_locale_and_db(self) -> (String, fontdb::Database) {
         (self.locale, self.db)
     }