Remove unused methods in PhabricatorEditorExtension

Summary:
The methods `newRequiredTransasctionError()` [sic!] and `newInvalidTransactionError()` are not called anywhere in the codebase. Both are `final protected`, thus remove them.

Incidentally, speedup Diviner generation by at least 0.000000000000000000000001 milliseconds.

Test Plan: Grep the code.

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed Committers, valerio.bozzolan

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25643

src/applications/transactions/engineextension/PhabricatorEditorExtension.php

@@ -66,18 +66,4 @@ abstract class PhabricatorEditorExtension
       $xaction);
   }
 
-  final protected function newRequiredTransasctionError(
-    PhabricatorApplicationTransaction $xaction,
-    $message) {
-    return $this->newError($xaction, pht('Required'), $message)
-      ->setIsMissingFieldError(true);
-  }
-
-  final protected function newInvalidTransactionError(
-    PhabricatorApplicationTransaction $xaction,
-    $message) {
-    return $this->newTransactionError($xaction, pht('Invalid'), $message);
-  }
-
-
 }