Avoid unnecessary usage of local vars

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

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

@@ -8,10 +8,7 @@
     .btn-group
       = inline_diff_btn
       = parallel_diff_btn
-  - additions = diff_files.sum(&:added_lines)
-  - deletions = diff_files.sum(&:removed_lines)
-  = render 'projects/diffs/stats', diff_files: diff_files,
-    additions: additions, deletions: deletions
+  = render 'projects/diffs/stats', diff_files: diff_files
 
 - if diff_files.count < diffs.size
   = render 'projects/diffs/warning', diffs: diffs, shown_files_count: diff_files.count

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

@@ -4,9 +4,9 @@
     = link_to '#', class: 'js-toggle-button' do
       %strong #{pluralize(diff_files.count, "changed file")}
     with
-    %strong.cgreen #{additions} additions
+    %strong.cgreen #{diff_files.sum(&:added_lines)} additions
     and
-    %strong.cred #{deletions} deletions
+    %strong.cred #{diff_files.sum(&:removed_lines)} deletions
   .file-stats.js-toggle-content.hide
     %ul
       - diff_files.each_with_index do |diff_file, i|