PORTLAND, Ore. — The Lakers built a 10-point lead late in the half, then gave a demonstration why it’s been so hard for them to win in the Rose Garden the last few seasons. They gave almost all of it away and the Trail Blazers closed to within four points. The Lakers shot 43.5 percent and the Blazers shot 39.5 percent. Kobe Bryant led the Lakers with 15 points, and Lamar Odom added 12 in a reserve role. Andrew Bynum had nine points and five rebounds in his second game back after a 32-game layup because of a right knee injury. Brandon Roy led Portland with 16 points.