[Ruby] Correct DBCS character handling

[zufuliu]

[Ruby] Correct DBCS character handling

[zufuliu]

I think the fix can be delayed untill there is bug in real code, also it not fix DBCS heredoc delimiter. Code use DBCS character (instead of ASCII or UTF-8) as identifier is non-portable.

# encoding: gbk
puts <<中
#{1+2}
中

[zufuliu]

Close this as won't fix. Move styler.IsLeadByte() to the end of for loop (before chPrev = ch;) seems will fix both problems, but it's hard to test due to advance_char(), redo_char() and InterpolateVariable() changes ch, chNext and chNext2.