Remove unneeded assert typescript declaration (#1841)
Remove unneeded assert typescript declaration (#1841)

The declaration is redundant after including `chai`.
parthea/datalab,parthea/datalab,googledatalab/datalab,parthea/datalab,googledatalab/datalab,parthea/datalab,parthea/datalab,parthea/datalab,googledatalab/datalab,googledatalab/datalab,googledatalab/datalab,googledatalab/datalab