[e] (0) Embrace the Encodings specification.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=17839
Affected topics: HTML, HTML Syntax and Parsing

git-svn-id: http://svn.whatwg.org/webapps@7647 340c8d12-0b0e-0410-8428-c7bf67bfef74
(cherry picked from commit 97ff321b55cdbabbe754a7f5863d5cce8af3b44d)

Replaces use of IANACHARSET with WHATWG encoding spec.