fix html_escape benchmark

benchmark/html_escape.rb

@@ -19,7 +19,7 @@ module HamlBench
 times = 100
 url = "http://en.wikipedia.org/wiki/Line_of_succession_to_the_British_throne"
 html = `curl -s #{url}`
-html = html.force_encoding('binary') if html.respond_to?(:force_encoding)
+html = html.force_encoding('utf-8') if html.respond_to?(:force_encoding)
 puts "Escaping #{html.bytesize} bytes of html #{times} times, from #{url}"
 
 Benchmark.bmbm do |x|