Always show build target tabs, even if they have no data

Summary:
Ref T8096. Hit this on IRC:

> epriestley: what's in the Messages tab?
> jdoe: what Messages tab??!
> epriestley: ughhhh

Test Plan: Clicked "Messages" tab, saw helpful "no messages" message.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T8096

Differential Revision: https://secure.phabricator.com/D13846

src/applications/harbormaster/controller/HarbormasterBuildViewController.php

@@ -172,34 +172,26 @@ final class HarbormasterBuildViewController
       }
 
       $details = $build_target->getDetails();
-      if ($details) {
       $properties = new PHUIPropertyListView();
       foreach ($details as $key => $value) {
         $properties->addProperty($key, $value);
       }
       $target_box->addPropertyList($properties, pht('Configuration'));
-      }
 
       $variables = $build_target->getVariables();
-      if ($variables) {
       $properties = new PHUIPropertyListView();
       $properties->addRawContent($this->buildProperties($variables));
       $target_box->addPropertyList($properties, pht('Variables'));
-      }
 
       $artifacts = $this->buildArtifacts($build_target);
-      if ($artifacts) {
       $properties = new PHUIPropertyListView();
       $properties->addRawContent($artifacts);
       $target_box->addPropertyList($properties, pht('Artifacts'));
-      }
 
       $build_messages = idx($messages, $build_target->getPHID(), array());
-      if ($build_messages) {
       $properties = new PHUIPropertyListView();
       $properties->addRawContent($this->buildMessages($build_messages));
       $target_box->addPropertyList($properties, pht('Messages'));
-      }
 
       $properties = new PHUIPropertyListView();
       $properties->addProperty(
@@ -243,11 +235,8 @@ final class HarbormasterBuildViewController
       ->withBuildTargetPHIDs(array($build_target->getPHID()))
       ->execute();
 
-    if (count($artifacts) === 0) {
-      return null;
-    }
-
     $list = id(new PHUIObjectItemListView())
+      ->setNoDataString(pht('This target has no associated artifacts.'))
       ->setFlush(true);
 
     foreach ($artifacts as $artifact) {