[FileReferencesInstaller] Compute groups less

lib/cocoapods/installer/xcode/pods_project_generator/file_references_installer.rb

@@ -115,8 +115,8 @@ module Pod
                 next unless sandbox.local?(pod_name)
                 root_name = Specification.root_name(pod_name)
                 paths = file_accessor.developer_files
-                paths.each do |path|
                 group = pods_project.group_for_spec(root_name, :developer)
+                paths.each do |path|
                   ref = pods_project.add_file_reference(path, group, false)
                   if path.extname == '.podspec'
                     pods_project.mark_ruby_file_ref(ref)
@@ -208,8 +208,8 @@ module Pod
               paths = file_accessor.send(file_accessor_key)
               paths = allowable_project_paths(paths)
               base_path = local ? common_path(paths) : nil
-              paths.each do |path|
               group = pods_project.group_for_spec(pod_name, group_key)
+              paths.each do |path|
                 pods_project.add_file_reference(path, group, local && reflect_file_system_structure_for_development, base_path)
               end
             end