Ruby

Fix memory leak with invalid yield in prism

[Bug #21383]

The following script leaks memory:

10.times do
  20_000.times do
    eval("class C; yield; end")
  rescue SyntaxError
  end

  puts `ps -o rss= -p #{$$}`
end

Before:

16464
25536
29424
35904
39552
44576
46736
51600
56096
59824

After:

13488
16160
18240
20528
19760
21808
21680
22272
22064
22336