Check symlink mode as a String for file_type_icon_class

See https://gitlab.com/gitlab-org/gitlab_git/commit/8ae14bb84b94a2ec15f8a639fb82f0f55c77ad69

app/helpers/icons_helper.rb

@@ -40,7 +40,7 @@ module IconsHelper
   def file_type_icon_class(type, mode, name)
     if type == 'folder'
       icon_class = 'folder'
-    elsif mode == 0120000
+    elsif mode == '120000'
       icon_class = 'share'
     else
       # Guess which icon to choose based on file extension.

spec/helpers/icons_helper_spec.rb

@@ -7,7 +7,7 @@ describe IconsHelper do
     end
 
     it 'returns share class' do
-      expect(file_type_icon_class('file', 0120000, 'link')).to eq 'share'
+      expect(file_type_icon_class('file', '120000', 'link')).to eq 'share'
     end
 
     it 'returns file-pdf-o class with .pdf' do