Import Parser::Builders::Default#dedent_string & Parser::Lexer::Dedenter#dedent
Import Parser::Builders::Default#dedent_string & Parser::Lexer::Dedenter#dedent

They'll be patched in a following commit, this import is there just to
maintain a clean diff.

opal/opal,opal/opal,Mogztter/opal,opal/opal,Mogztter/opal,Mogztter/opal,opal/opal,Mogztter/opal