Remove "Child Revisions" custom field in Differential

Summary: Ref T11114. This was obsoleted by the "Stack" graph and does nothing.

Test Plan: Viewed revisions, still saw dependency graphs.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11114

Differential Revision: https://secure.phabricator.com/D17072

src/applications/differential/config/PhabricatorDifferentialConfigOptions.php

@@ -40,7 +40,6 @@ final class PhabricatorDifferentialConfigOptions
       new DifferentialEditPolicyField(),
 
       new DifferentialParentRevisionsField(),
-      new DifferentialChildRevisionsField(),
       new DifferentialManiphestTasksField(),
       new DifferentialCommitsField(),
 

src/applications/differential/customfield/DifferentialChildRevisionsField.php

@@ -1,22 +0,0 @@
-<?php
-
-final class DifferentialChildRevisionsField
-  extends DifferentialCustomField {
-
-  public function getFieldKey() {
-    return 'differential:dependencies';
-  }
-
-  public function getFieldName() {
-    return pht('Child Revisions');
-  }
-
-  public function canDisableField() {
-    return false;
-  }
-
-  public function getFieldDescription() {
-    return pht('Lists revisions this one is depended on by.');
-  }
-
-}