Ruby

Remove unnecessary assignment to ast->body.line_count

This patch removes a code that assigns -1 to ast->body.line_count because, at least as of now, it looks not necessary.
I made this commit atomically revertable if I was wrong.

Relevant commits¶

• The preparation for this PR: https://github.com/ruby/ruby/pull/10655/files#diff-2af2e7f2e1c28da5e9d99ad117cba1c4dabd8b0bc3081da88e414c55c6aa9549R1484-R1493
• The original commit that introduced the code: https://github.com/ruby/ruby/commit/d65f7458bc8b4fa4404c41713cfa1ece5260fc8a