[ruby/irb] fix indent depth calculation after heredoc and embdoc

https://github.com/ruby/irb/commit/b7973dd2d2

lib/irb/ruby-lex.rb

@@ -643,7 +643,7 @@ class RubyLex
       end
 
       case t.event
-      when :on_ignored_nl, :on_nl, :on_comment
+      when :on_ignored_nl, :on_nl, :on_comment, :on_heredoc_end, :on_embdoc_end
         if in_oneliner_def != :BODY
           corresponding_token_depth = nil
           spaces_at_line_head = 0