Converter update for Big5, KOI8-U and timezone update to 2015g

* Big5 : https://www.w3.org/Bugs/Public/show_bug.cgi?id=27878

  Special case the following four more code points in
  addition to U+5341, U+5345 that are already special cased.

      U+2550, U+255E, U+2561, U+256A

  For those 6 code points, the last pointer instead of the first pointer
  in index-big5.txt is used for round-trip. The first pointer is for
  decoding-only.

* KOI8-U ( https://www.w3.org/Bugs/Public/show_bug.cgi?id=17053 )

  - 0xAE and 0xBE are mapped to U+04[50]E instead of U+255[DC].
  - Add an alias KOI8-RU

BUG=544228
TEST=1. http://goo.gl/reGQPU :  encoding(form) test
 2. Layout test: fast/encoding/*

R=jsbell@chromium.org

Review URL: https://codereview.chromium.org/1514253003 .
15 files changed