FORT LAUDERDALE — The Panthers were in desperate need of a goal, and Matthew Tkachuk supplied it. Tkachuk’s second-period goal, his first since the first game of the Eastern Conference finals, cut Florida’s deficit to 3-1 and woke the despondent crowd at Amerant Bank Arena. Although the Panthers eventually lost 5-3, dropping their second straight Stanley Cup Final game, Tkachuk’s strong performance offered promise that the star winger might be out of his playoff drought just in time for Florida to clinch its first-ever Stanley Cup in Game 6 in Edmonton at 8 p.m.