[SPV]

Мишань, а так:

function order (a, b) {
   if (a.x < b.x) {
     return -1;
   } else if (a.x > b.x) {
     return 1;
   } else {
     return 0;
   }
 }

function retrace (what) {
	trace ("");
	for (var i = 0; i<what.length; i++) {
		trace (i+" :: "+"{x: "+what[i].x+" ; y: "+what[i].y+"}");
	}
}
// 
test = [{x:150, y:20}, {x:50, y:20}, {x:200, y:20}, {x:10, y:20}, {x:100, y:20}];
// 
retrace(test);
test.sort(order);
retrace(test);