It can be used to get the parameters' information of method and block.
There was no way to get block parameters.
It was possible but ineffective to get method parameters via Method
object: `tp.defined_class.method(tp.method_id).parameters`
TracePoint#parameters allows us to get the information easily.
[Feature #14694]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63562 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
