Fix Diffusion fatal with symbol highlighting

Summary: This returns a list of PHIDs, not objects which need to be pulled.

Test Plan:
Repro'd fatal locally, verified it was fixed.

Repro steps are:

  - Create an arc project associated with a repository, with indexed language(s) and subprojects.
  - View a file in that repository.

Reviewers: nh, btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D3038

src/applications/diffusion/controller/DiffusionBrowseFileController.php

@@ -220,7 +220,6 @@ final class DiffusionBrowseFileController extends DiffusionController {
             continue;
           }
           $dep_projects = $project->getSymbolIndexProjects();
-          $dep_projects = mpull($dep_projects, 'getPHID');
           $dep_projects[] = $project->getPHID();
           foreach ($ls as $lang) {
             if (!isset($langs[$lang])) {