Propagate more return codes up the chain from the token emitter.
Propagate more return codes up the chain from the token emitter.

svn path=/trunk/hubbub/; revision=4980

Achal-Aggarwal/hibbub,servo/libhubbub,Achal-Aggarwal/hibbub,servo/libhubbub,adamwight/wmf-parsoid-libhubbub,prepare/netsurf_libhubbub,servo/libhubbub,Achal-Aggarwal/hibbub,prepare/netsurf_libhubbub,servo/libhubbub,Achal-Aggarwal/hibbub,prepare/netsurf_libhubbub,adamwight/wmf-parsoid-libhubbub,servo/libhubbub,prepare/netsurf_libhubbub,prepare/netsurf_libhubbub,adamwight/wmf-parsoid-libhubbub,prepare/netsurf_libhubbub,adamwight/wmf-parsoid-libhubbub,adamwight/wmf-parsoid-libhubbub