* TSX down 50.97 pts, or 0.4 pct, to 11,820.26 * Materials, energy issues fall more than 1 pct * Financials pare some losses * Greek, French election results hurt sentiment By Jon Cook TORONTO, May 7 (Reuters) - Toronto's main stock index was on track for its fourth straight loss on Monday as oil and other resource-based commodities tumbled after Greek and French election results rattled investors. Euro zone debt fears escalated after incumbent governments in France a