def read_bower_main(dirname, filename)
      bower = JSON.parse(File.read(filename), create_additions: false)

      case bower['main']
      when String
        yield File.expand_path(bower['main'], dirname)
      when Array
        bower['main'].each do |name|
          yield File.expand_path(name, dirname)
        end
      end
    end
def read_bower_main(dirname, filename)
      bower = JSON.parse(File.read(filename), create_additions: false)

      case bower['main']
      when String
        yield File.expand_path(bower['main'], dirname)
      when Array
        bower['main'].each do |name|
          yield File.expand_path(name, dirname)
        end
      end
    end
Internal: Read bower.json's main directive.

 dirname  - String path to component directory.
 filename - String path to bower.json.

 Returns nothing.