ROUGH CUT (NO REPORTER NARRATION)<br/> <br />STORY: Protesters clashed with police in Turkey's two biggest cities on Tuesday after the death of a 15-year-old boy who was hit in the head by a tear-gas canister during anti-government demonstrations last summer.<br/> <br />Police fired water cannon and tear gas to disperse crowds in Istanbul and Ankara, the latest pre-election headache for Prime Minister Tayyip Erdogan, already battling a graft scandal which has become one of the biggest challenges of his decade in power.<br/> <br />Berkin Elvan, then 14, got caught up in street battles in Istanbul between police and protesters on June 16 while going to buy bread for his family. He slipped into a coma and became a rallying point for government opponents, who held regular vigils at the hospital where he lay in intensive care.<br/> <br />Elvan was the sixth person to die in violence during nationwide protests in late May and June over Erdogan's plans to bulldoze an Istanbul park. The protests turned into one o
