This fixes almost all of CRuby test_proc.rb remaining cases, except for this one which I think needs either parser or compiler help (assignments to the implicit it parameter should be a no-op?):

TestProc#test_implicit_parameters_for_it_complex [/Users/headius/work/jruby/test/mri/ruby/test_proc.rb:1869]:
<"foo"> expected but was
<"bar">.