By Nidal al-Mughrabi CAIRO, June 8 (Reuters) - Israeli strikes killed four Palestinians, including a child, in the Gaza Strip on Monday, health officials there said, as Israel's military expanded the area under its control, according to residents. The reports came as mediators in Cairo said they were pressing on with efforts to salvage a fragile U.S.-brokered ceasefire deal that has ended major clashes but left many key points unresolved.