Revert "Issue #2952634 by Sut3kh, alexpott, Rob C, jibran:...

Revert "Issue #2952634 by Sut3kh, alexpott, Rob C, jibran: LegacyMessenger::deleteByType does not delete anything"

This reverts commit cbe0ec99.

core/lib/Drupal/Core/Messenger/LegacyMessenger.php

@@ -180,7 +180,7 @@ public function deleteAll() {
   public function deleteByType($type) {
     // Proxy to the Messenger service, if it exists.
     if ($messenger = $this->getMessengerService()) {
-      return $messenger->deleteByType($type);
+      return $messenger->messagesByType($type);
     }
 
     $messages = static::$messages[$type];

core/modules/file/src/Tests/SaveUploadFormTest.php

@@ -419,7 +419,7 @@ public function testErrorMessagesAreNotChanged() {
     // after calling _file_save_upload_from_form() are correct.
     $this->assertText($error);
     $this->assertRaw('Number of error messages before _file_save_upload_from_form(): 1');
-    $this->assertRaw('Number of error messages after _file_save_upload_from_form(): 1');
+    $this->assertRaw('Number of error messages after _file_save_upload_from_form(): 2');
 
     // Test a successful upload with no messages.
     $edit = [

core/tests/Drupal/KernelTests/Core/Messenger/MessengerLegacyTest.php

@@ -103,11 +103,6 @@ public function testMessages() {
     $this->assertCount(4, $messages[MessengerInterface::TYPE_STATUS]);
     $this->assertCount(4, $messages[MessengerInterface::TYPE_WARNING]);
     $this->assertCount(4, $messages[MessengerInterface::TYPE_ERROR]);
-
-    // Test deleteByType().
-    $this->assertCount(4, $messenger->deleteByType(MessengerInterface::TYPE_WARNING));
-    $this->assertCount(0, $messenger->messagesByType(MessengerInterface::TYPE_WARNING));
-    $this->assertCount(4, $messenger->messagesByType(MessengerInterface::TYPE_ERROR));
   }
 
 }