changed InlineDiffMarker to make it html_safe its output

updated the spec

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

@@ -17,7 +17,7 @@
     = blob_icon diff_file.b_mode, diff_file.file_path
 
     - if diff_file.renamed_file?
-      - old_path, new_path = mark_inline_diffs(diff_file.old_path, diff_file.new_path).map(&:html_safe)
+      - old_path, new_path = mark_inline_diffs(diff_file.old_path, diff_file.new_path)
       %strong.file-title-name.has-tooltip{ data: { title: diff_file.old_path, container: 'body' } }
         = old_path
       →

lib/gitlab/diff/inline_diff_marker.rb

@@ -2,9 +2,10 @@ module Gitlab
   module Diff
     class InlineDiffMarker < Gitlab::StringRangeMarker
       def mark(line_inline_diffs, mode: nil)
-        super(line_inline_diffs) do |text, left:, right:|
+        mark = super(line_inline_diffs) do |text, left:, right:|
           %{<span class="#{html_class_names(left, right, mode)}">#{text}</span>}
         end
+        mark.html_safe
       end
 
       private

spec/helpers/diff_helper_spec.rb

@@ -136,9 +136,9 @@ describe DiffHelper do
       marked_old_line, marked_new_line = mark_inline_diffs(old_line, new_line)
 
       expect(marked_old_line).to eq(%q{abc <span class="idiff left right deletion">'def'</span>})
-      expect(marked_old_line).not_to be_html_safe
+      expect(marked_old_line).to be_html_safe
       expect(marked_new_line).to eq(%q{abc <span class="idiff left right addition">"def"</span>})
-      expect(marked_new_line).not_to be_html_safe
+      expect(marked_new_line).to be_html_safe
     end
   end