Avoid line_code and position calculation on line partial for plain view

CHANGELOG

@@ -32,6 +32,7 @@ v 8.11.0 (unreleased)
   - Add the `sprockets-es6` gem
   - Multiple trigger variables show in separate lines (Katarzyna Kobierska Ula Budziszewska)
   - Profile requests when a header is passed
+  - Avoid calculation of line_code and position for _line partial when showing diff notes on discussion tab.
   - Add commit stats in commit api. !5517 (dixpac)
   - Make error pages responsive (Takuya Noguchi)
   - Change requests_profiles resource constraint to catch virtually any file

app/views/projects/diffs/_line.html.haml

 - plain = local_assigns.fetch(:plain, false)
-- line_code = diff_file.line_code(line)
-- position = diff_file.position(line)
 - type = line.type
-%tr.line_holder{ id: line_code, class: type }
+- line_code = diff_file.line_code(line) unless plain
+%tr.line_holder{ plain ? { class: type} : { class: type, id: line_code } }
   - case type
   - when 'match'
     = render "projects/diffs/match_line", { line: line.text,
@@ -24,4 +23,4 @@
         = link_text
       - else
         %a{href: "##{line_code}", data: { linenumber: link_text }}
-    %td.line_content.noteable_line{ class: type, data: (diff_view_line_data(line_code, position, type) unless plain) }= diff_line_content(line.text, type)
+    %td.line_content.noteable_line{ class: type, data: (diff_view_line_data(line_code, diff_file.position(line), type) unless plain) }= diff_line_content(line.text, type)