add spec for CLI option '-W:no-experimental' using RUBYOPT
add spec for CLI option '-W:no-experimental' using RUBYOPT

Commit e5d3e4d8 introduced spec for '-W:no-experimental' CLI option. This commit asserts the same result if the option is defined in the RUBYOPT environment variable.

nobu/rubyspec,nobu/rubyspec,nobu/rubyspec,ruby/spec,ruby/spec,ruby/spec