Don't throw if translating before loading

Just return the passed string. This makes initialisation simpler, as a
promise is unnecessary.

src/gui/html/js/translator.js

@@ -67,6 +67,9 @@
       if (text === undefined) {
         return '';
       }
+      if (this.jed === undefined) {
+        return text;
+      }
       const func = this.jed.translate(text);
       return func.fetch.apply(func, substitutions);
     }

src/tests/gui/html/js/test_translator.js

@@ -37,8 +37,8 @@ describe('Translator', () => {
       l10n = new loot.Translator();
     });
 
-    it('should throw if the translator has not been loaded', () => {
-      (() => { l10n.translate('foo'); }).should.throw();
+    it('should return original string if the translator has not been loaded', () => {
+      l10n.translate('foo').should.equal('foo');
     });
 
     it('should return an empty string if nothing is passed', () => {