`using` in Refinements should be physically placed before the refined method call

doesnot_work.rb

class String
  def bar() foo; end
end

using Module.new {
  refine String do
    def foo() p self; end
  end
}

'hello'.bar

#=> doesnot_work.rb:2:in `bar': undefined local variable or method `foo' for "hello":String (NameError)

works.rb

using Module.new {
  refine String do
    def foo() p self; end
  end
}

class String
  def bar() foo; end
end

'hello'.bar

#=> "hello"