By Lisa Barrington BEIRUT (Reuters) – Syrian rebels agreed to surrender a second besieged enclave in eastern Ghouta on Friday as their comrades in another insurgent pocket in the area continued their withdrawal after a month-long assault by the army. It will leave only one remaining rebel pocket in eastern Ghouta – the city of Douma – and put Syrian President Bashar al-Assad on the brink of his biggest victory over the insurgents since driving them from Aleppo in December 2016. Insurgents in one of those pockets – the town of Harasta – began withdrawing in a convoy of buses for opposition territory in northwestern Syria on Thursday.