Does Syrian law, which stipulates that the grandchildren of a deceased woman who died before her father are deprived of inheritance, conform to Islamic Sharia, and if they do have a share, what is its extent?

The grandchild does not inherit from his maternal grandfather, because the daughter's son is not originally among the heirs. Rather, he is among the uterine kin (dhawu al-arham) who inherit only when there is no heir by fixed share or residuary right.