* 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/obj.js

@@ -574,7 +574,8 @@ var XRef = (function XRefClosure() {
       if (dict)
         return dict;
       // nothing helps
-      error('Invalid PDF structure');
+      // calling error() would reject worker with an UnknownErrorException.
+      throw new InvalidPDFException('Invalid PDF structure');
     },
     readXRef: function XRef_readXRef(startXRef, recoveryMode) {
       var stream = this.stream;