Remove unused #tree-holder

app/views/projects/_files.html.haml

 - commit = local_assigns.fetch(:commit) { @repository.commit }
 - ref = local_assigns.fetch(:ref) { current_ref }
 - project = local_assigns.fetch(:project) { @project }
-#tree-holder.tree-holder.clearfix
+.tree-holder.clearfix
   .nav-block
     = render 'projects/tree/tree_header', tree: @tree
 

app/views/projects/artifacts/file.html.haml

@@ -3,7 +3,7 @@
 
 = render "projects/jobs/header", show_controls: false
 
-#tree-holder.tree-holder
+.tree-holder
   .nav-block
     %ul.breadcrumb.repo-breadcrumb
       %li

app/views/projects/blob/show.html.haml

@@ -10,7 +10,7 @@
 = render 'projects/last_push'
 
 %div{ class: container_class }
-  #tree-holder.tree-holder
+  .tree-holder
     = render 'blob', blob: @blob
 
   - if can_modify_blob?(@blob)