* InvalidPDFException added

* Act on throwing an Exception and InvalidPDFException by rejecting the worker
instead of throwing
* changed message for all builds
* alerting and closing window only for B2G builds
* invalid_file_error added to l10n (en and pl)
* UnknownErrorException added and used for every error()

src/worker.js

@@ -124,9 +124,19 @@ var WorkerMessageHandler = {
             });
           }
 
+          return;
+        } else if (e instanceof InvalidPDFException) {
+          handler.send('InvalidPDF', {
+            exception: e
+          });
+
           return;
         } else {
-          throw e;
+          handler.send('UnknownError', {
+            exception: new UnknownErrorException(e.message, e.toString())
+          });
+
+          return;
         }
       }
       var doc = {
@@ -331,4 +341,3 @@ if (typeof window === 'undefined') {
   var handler = new MessageHandler('worker_processor', this);
   WorkerMessageHandler.setup(handler);
 }
-