“It is worth reiterating at this juncture that the role of the court under s. 23 [of the Children’s Law Reform Act] is to determine whether the party invoking the section has established, on a balance of probabilities, that a child will suffer serious harm if an Ontario court does not assume jurisdiction. For the law of the UAE to qualify as serious harm, that harm would have to be clearly established on the evidence. It is not enough to point to differences in the law and suggest that a parent may have different rights in a foreign jurisdiction vis-à-vis Ontario. The serious harm test in s. 23 of the CLRA, which was implemented to protect the safety of children, must not be reduced to a means for Ontario courts to prefer this province’s system of justice over those of foreign jurisdictions under the guise of child safety.”