Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>

The following is crashing for me:

```shell
ruby --yjit --yjit-call-threshold=1 -e '1.tap { raise rescue p it }'

ruby: YJIT has panicked. More info to follow...
thread '<unnamed>' panicked at ./yjit/src/codegen.rs:2402:14:
...
```

It seems `it` sometimes points to the wrong value:

```shell
ruby -e '1.tap { raise rescue p it }'
false

ruby -e '1.tap { begin; raise; ensure; p it; end } rescue nil'
false
```

But only when `$!` is set:

```shell
ruby -e '1.tap { begin; nil; ensure; p it; end }'
1

ruby -e '1.tap { begin; nil; rescue; ensure; p it; end }'
1

ruby -e '1.tap { begin; raise; rescue; ensure; p it; end }'
1
```

This reverts commit 7adf89d7ad30552d7e57709d24eec266f601d38b.

	[PRISM] Handle forwarding inside eval

	Fixes [Bug #21031]

Revert "[Bug #20965] Define `it` like an ordinary argument (#12398)"

Reverts ruby/ruby#12398 as per https://bugs.ruby-lang.org/issues/20970#note-6 and https://bugs.ruby-lang.org/issues/20965#note-7.
We need more time to design the intended behavior, and it's too late for Ruby 3.4.

Also fixes [Bug #20955]

If there is a syntax error, there could be an ast_node in the result.
This could get leaked if there is a syntax error so parsing could not
complete (parsed is not set to true).

For example, the following script leaks memory:

    10.times do
      10_000.times do
        eval("def foo(...) super(...) {}; end")
      rescue SyntaxError
      end

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

Before:

    31328
    42768
    53856
    65120
    76208
    86768
    97856
    109120
    120208
    131296

After:

    20944
    20944
    20944
    20944
    20944
    20944
    20944
    20944
    20944
    20944

```
-:3: warning: assigned but unused variable - var
-:3: warning: assigned but unused variable - var
-:3: warning: assigned but unused variable - var
-:3: warning: assigned but unused variable - var
-:3: warning: assigned but unused variable - var
-:3: warning: assigned but unused variable - var
```