Small fix to the Lexer to prevent identifiers from containing '\', since it was listed as an identifier character.
Small fix to the Lexer to prevent identifiers from containing '\', since it was listed as an identifier character.

Prevents:
var a\u005C = 'foo'

Signed-off-by: John Gietzen <565533dc8fd10856192adc18fcbade0f182446ed@gietzen.us>

xamarin/IronJS,hnafar/IronJS,hnafar/IronJS,fholm/IronJS,hnafar/IronJS,fholm/IronJS,fholm/IronJS,xamarin/IronJS,xamarin/IronJS,fholm/IronJS,hnafar/IronJS,xamarin/IronJS,hnafar/IronJS