Fix handling method parmeter

  def a, b, # comment
      c
  end

This is valid definition of method with a comment inside args.
This commit fixes behavior for it.

Author: aycabta

lib/rdoc/parser/ruby.rb

@@ -1541,7 +1541,7 @@ def parse_method_or_yield_parameters(method = nil,
             unget_tk tk
             read_documentation_modifiers method, modifiers
           end
-          break if nest <= 0
+          break if !continue and nest <= 0
         end
       when :on_comma then
         continue = true