fix for ROOT-6699: check that a class is valid before downcasting
fix for ROOT-6699: check that a class is valid before downcasting

omazapa/root-old,karies/root,olifre/root,lgiommi/root,dfunke/root,krafczyk/root,arch1tect0r/root,zzxuanyuan/root-compressor-dummy,satyarth934/root,olifre/root,jrtomps/root,root-mirror/root,bbockelm/root,buuck/root,mkret2/root,agarciamontoro/root,evgeny-boger/root,georgtroska/root,mhuwiler/rootauto,omazapa/root-old,thomaskeck/root,karies/root,omazapa/root-old,jrtomps/root,satyarth934/root,CristinaCristescu/root,beniz/root,veprbl/root,satyarth934/root,mkret2/root,esakellari/root,arch1tect0r/root,esakellari/my_root_for_test,perovic/root,davidlt/root,arch1tect0r/root,mattkretz/root,sawenzel/root,satyarth934/root,abhinavmoudgil95/root,bbockelm/root,georgtroska/root,davidlt/root,thomaskeck/root,mhuwiler/rootauto,buuck/root,gganis/root,mattkretz/root,evgeny-boger/root,sbinet/cxx-root,esakellari/my_root_for_test,perovic/root,thomaskeck/root,davidlt/root,BerserkerTroll/root,abhinavmoudgil95/root,zzxuanyuan/root,omazapa/root,perovic/root,gbitzes/root,Y--/root,karies/root,abhinavmoudgil95/root,abhinavmoudgil95/root,omazapa/root,sbinet/cxx-root,beniz/root,root-mirror/root,dfunke/root,beniz/root,abhinavmoudgil95/root,veprbl/root,Duraznos/root,root-mirror/root,lgiommi/root,jrtomps/root,sirinath/root,esakellari/my_root_for_test,zzxuanyuan/root-compressor-dummy,agarciamontoro/root,buuck/root,lgiommi/root,omazapa/root-old,krafczyk/root,bbockelm/root,sbinet/cxx-root,thomaskeck/root,sbinet/cxx-root,dfunke/root,nilqed/root,esakellari/root,nilqed/root,esakellari/my_root_for_test,georgtroska/root,veprbl/root,mhuwiler/rootauto,perovic/root,vukasinmilosevic/root,buuck/root,zzxuanyuan/root,karies/root,gbitzes/root,zzxuanyuan/root,nilqed/root,thomaskeck/root,Duraznos/root,buuck/root,mattkretz/root,beniz/root,vukasinmilosevic/root,georgtroska/root,buuck/root,georgtroska/root,sbinet/cxx-root,esakellari/my_root_for_test,sawenzel/root,davidlt/root,satyarth934/root,dfunke/root,CristinaCristescu/root,arch1tect0r/root,evgeny-boger/root,esakellari/my_root_for_test,pspe/root,zzxuanyuan/root-compressor-dummy,omazapa/root,buuck/root,karies/root,mkret2/root,CristinaCristescu/root,evgeny-boger/root,beniz/root,satyarth934/root,dfunke/root,omazapa/root,mattkretz/root,mkret2/root,esakellari/root,evgeny-boger/root,evgeny-boger/root,arch1tect0r/root,CristinaCristescu/root,karies/root,beniz/root,gbitzes/root,sbinet/cxx-root,simonpf/root,pspe/root,gganis/root,beniz/root,CristinaCristescu/root,jrtomps/root,BerserkerTroll/root,gbitzes/root,agarciamontoro/root,olifre/root,agarciamontoro/root,zzxuanyuan/root,zzxuanyuan/root-compressor-dummy,zzxuanyuan/root-compressor-dummy,gbitzes/root,omazapa/root-old,Y--/root,root-mirror/root,gganis/root,BerserkerTroll/root,BerserkerTroll/root,davidlt/root,pspe/root,sawenzel/root,evgeny-boger/root,agarciamontoro/root,root-mirror/root,BerserkerTroll/root,sawenzel/root,omazapa/root-old,sawenzel/root,pspe/root,Duraznos/root,veprbl/root,krafczyk/root,Duraznos/root,gbitzes/root,perovic/root,davidlt/root,lgiommi/root,olifre/root,Y--/root,Duraznos/root,zzxuanyuan/root,beniz/root,simonpf/root,omazapa/root,zzxuanyuan/root-compressor-dummy,abhinavmoudgil95/root,mattkretz/root,thomaskeck/root,nilqed/root,Duraznos/root,mattkretz/root,esakellari/root,sirinath/root,veprbl/root,perovic/root,arch1tect0r/root,satyarth934/root,simonpf/root,krafczyk/root,Duraznos/root,mattkretz/root,mkret2/root,esakellari/root,mkret2/root,krafczyk/root,esakellari/root,omazapa/root-old,mhuwiler/rootauto,sawenzel/root,agarciamontoro/root,mkret2/root,jrtomps/root,zzxuanyuan/root,BerserkerTroll/root,CristinaCristescu/root,lgiommi/root,lgiommi/root,sbinet/cxx-root,vukasinmilosevic/root,veprbl/root,bbockelm/root,BerserkerTroll/root,nilqed/root,root-mirror/root,bbockelm/root,zzxuanyuan/root-compressor-dummy,gganis/root,gbitzes/root,buuck/root,olifre/root,mattkretz/root,BerserkerTroll/root,gbitzes/root,karies/root,satyarth934/root,vukasinmilosevic/root,buuck/root,esakellari/root,olifre/root,bbockelm/root,arch1tect0r/root,arch1tect0r/root,evgeny-boger/root,jrtomps/root,sirinath/root,sirinath/root,beniz/root,bbockelm/root,CristinaCristescu/root,mattkretz/root,root-mirror/root,Y--/root,gganis/root,nilqed/root,esakellari/root,sawenzel/root,evgeny-boger/root,krafczyk/root,veprbl/root,gbitzes/root,agarciamontoro/root,CristinaCristescu/root,Y--/root,bbockelm/root,sirinath/root,perovic/root,esakellari/root,omazapa/root,omazapa/root,karies/root,gganis/root,omazapa/root-old,satyarth934/root,Duraznos/root,dfunke/root,vukasinmilosevic/root,karies/root,sbinet/cxx-root,zzxuanyuan/root,mkret2/root,omazapa/root,pspe/root,davidlt/root,mkret2/root,davidlt/root,karies/root,esakellari/root,perovic/root,mkret2/root,perovic/root,thomaskeck/root,sawenzel/root,CristinaCristescu/root,lgiommi/root,krafczyk/root,zzxuanyuan/root-compressor-dummy,pspe/root,georgtroska/root,thomaskeck/root,omazapa/root-old,veprbl/root,abhinavmoudgil95/root,dfunke/root,simonpf/root,buuck/root,BerserkerTroll/root,gganis/root,abhinavmoudgil95/root,abhinavmoudgil95/root,zzxuanyuan/root-compressor-dummy,vukasinmilosevic/root,nilqed/root,evgeny-boger/root,agarciamontoro/root,gganis/root,mhuwiler/rootauto,Duraznos/root,lgiommi/root,olifre/root,thomaskeck/root,sirinath/root,sbinet/cxx-root,dfunke/root,dfunke/root,zzxuanyuan/root,Y--/root,esakellari/my_root_for_test,Y--/root,georgtroska/root,Duraznos/root,pspe/root,evgeny-boger/root,jrtomps/root,root-mirror/root,bbockelm/root,jrtomps/root,Y--/root,lgiommi/root,zzxuanyuan/root,simonpf/root,root-mirror/root,root-mirror/root,vukasinmilosevic/root,veprbl/root,Y--/root,pspe/root,perovic/root,omazapa/root-old,karies/root,omazapa/root,sawenzel/root,bbockelm/root,simonpf/root,mhuwiler/rootauto,mattkretz/root,esakellari/my_root_for_test,olifre/root,CristinaCristescu/root,mhuwiler/rootauto,vukasinmilosevic/root,arch1tect0r/root,dfunke/root,arch1tect0r/root,Duraznos/root,georgtroska/root,zzxuanyuan/root,veprbl/root,sbinet/cxx-root,jrtomps/root,olifre/root,gbitzes/root,georgtroska/root,satyarth934/root,arch1tect0r/root,zzxuanyuan/root-compressor-dummy,beniz/root,root-mirror/root,buuck/root,zzxuanyuan/root-compressor-dummy,pspe/root,simonpf/root,georgtroska/root,simonpf/root,agarciamontoro/root,satyarth934/root,nilqed/root,sawenzel/root,sirinath/root,vukasinmilosevic/root,esakellari/my_root_for_test,olifre/root,olifre/root,simonpf/root,BerserkerTroll/root,mattkretz/root,zzxuanyuan/root,sirinath/root,omazapa/root,vukasinmilosevic/root,sbinet/cxx-root,krafczyk/root,thomaskeck/root,mhuwiler/rootauto,gganis/root,lgiommi/root,mkret2/root,dfunke/root,simonpf/root,mhuwiler/rootauto,davidlt/root,nilqed/root,gbitzes/root,beniz/root,Y--/root,esakellari/root,nilqed/root,omazapa/root,veprbl/root,CristinaCristescu/root,bbockelm/root,sirinath/root,agarciamontoro/root,mhuwiler/rootauto,vukasinmilosevic/root,lgiommi/root,Y--/root,sawenzel/root,esakellari/my_root_for_test,mhuwiler/rootauto,gganis/root,perovic/root,krafczyk/root,davidlt/root,nilqed/root,simonpf/root,pspe/root,krafczyk/root,davidlt/root,abhinavmoudgil95/root,zzxuanyuan/root,gganis/root,abhinavmoudgil95/root,jrtomps/root,BerserkerTroll/root,georgtroska/root,omazapa/root-old,pspe/root,krafczyk/root,jrtomps/root,sirinath/root,agarciamontoro/root,sirinath/root