adjust special scheme/class keywords to effectively declare themselves as expression forms (PR 10135): merge to 4.1.5
adjust special scheme/class keywords to effectively declare themselves as expression forms (PR 10135): merge to 4.1.5

svn: r14137

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket