# File lib/uglifier.rb, line 84
  def initialize(options = {})
    (options.keys - DEFAULTS.keys - [:comments, :squeeze, :copyright])[0..1].each do |missing|
      raise ArgumentError.new("Invalid option: #{missing}")
    end
    @options = options
    @context = ExecJS.compile(File.open(ES5FallbackPath, "r:UTF-8").read +
                              File.open(SplitFallbackPath, "r:UTF-8").read +
                              File.open(SourcePath, "r:UTF-8").read)
  end