By Alexander Cornwell TEL AVIV, June 26 (Reuters) - Israel's former military chief Gadi Eisenkot, who lost a son in Gaza and boasts of his "Dahiyeh doctrine" of smashing foes with disproportionate force, is surging in polls and could oust Benjamin Netanyahu as prime minister in a coming election. Eisenkot, 66, has projected an image as a political outsider, soldier and security hawk whose humble background and family sacrifices stand in vivid contrast to Netanyahu's decades in high office and lingering corruption cases.