[giow] (2) Add greek to the default encoding logic.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=23090
Affected topics: HTML Syntax and Parsing

git-svn-id: http://svn.whatwg.org/webapps@8259 340c8d12-0b0e-0410-8428-c7bf67bfef74