Combination Chemotherapy in Treating Young Patients With Advanced Solid Tumors

childhood central nervous system choriocarcinoma, childhood central nervous system embryonal tumor, childhood central nervous system germ cell tumor, childhood central nervous system germinoma, childhood central nervous system mixed germ cell tumor, childhood central nervous system teratoma, childhood central nervous system yolk sac tumor, recurrent childhood brain stem glioma, recurrent childhood central nervous system embryonal tumor, unspecified childhood solid tumor, protocol specific, interventional, phase1