rubinius/rubinius — pull request #1582 by roshats (2012-03-03 09:34:42+00:00)
Title: regards named parameters in procs as optional

Fix Proc#parameters to mark arguments without default values as optional.

rubinius before commit:
```Proc.new{|a| }.parameters #=> [[:req, :a]]```
```Proc.new{|a, b = 1, c| }.parameters #=> [[:req, :a], [:opt, :b], [:req, :c]]```

1.9.2, 1.9.3, rubinius after commit:
```Proc.new{|a| }.parameters #=> [[:opt, :a]]```
```Proc.new{|a, b = 1, c| }.parameters #=> [[:opt, :a], [:opt, :b], [:opt, :c]]```