class Bundler::Dependency

def gem_platforms(valid_platforms)

passed in the `valid_platforms` parameter
Returns the platforms this dependency is valid for, in the same order as 
def gem_platforms(valid_platforms)
  return [Gem::Platform::RUBY] if force_ruby_platform
  return valid_platforms if @platforms.empty?
  valid_platforms.select {|p| expanded_platforms.include?(GemHelpers.generic(p)) }
end