Remove duplicated initialization of stack_parameter_count_ of hydrogen stub descriptor.

R=verwaest@chromium.org

Review URL: https://chromiumcodereview.appspot.com/16097004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14897 ce2b1a6d-e550-0410-aec6-3dcde31c8c00