Fix using UTF-8 characters with :html_safe escaping

Fixes #113.

Author: devinus

lib/poison/encoder.ex

@@ -164,10 +164,6 @@ defimpl Poison.Encoder, for: BitString do
     ["\\/" | escape(rest, :html_safe)]
   end
 
-  defp escape(<<char::utf8>> <> rest, :html_safe) do
-    [char | escape(rest, :html_safe)]
-  end
-
   defp escape(string, mode) do
     size = chunk_size(string, mode, 0)
     <<chunk::binary-size(size), rest::binary>> = string
@@ -179,6 +175,10 @@ defimpl Poison.Encoder, for: BitString do
     acc
   end
 
+  defp chunk_size(<<?/::utf8>> <> _, :html_safe, acc) do
+    acc
+  end
+
   defp chunk_size(<<char>> <> rest, mode, acc) when char < 0x80 do
     chunk_size(rest, mode, acc + 1)
   end

test/poison/encoder_test.exs

@@ -32,6 +32,9 @@ defmodule Poison.EncoderTest do
     assert to_json("\u2028\u2029", escape: :javascript) == ~s("\\u2028\\u2029")
     assert to_json("</script>", escape: :html_safe) == ~s("<\\/script>")
 
+    assert to_json("\uCCCC</script>\uCCCC", escape: :html_safe) ==
+             ~s("쳌<\\/script>쳌")
+
     assert to_json(~s(<script>var s = "\u2028\u2029";</script>),
              escape: :html_safe
            ) == ~s("<script>var s = \\\"\\u2028\\u2029\\\";<\\/script>")