perf(orderBy): copy array with slice instead of for loop
perf(orderBy): copy array with slice instead of for loop

Use array slice method to copy entire array instead of a for loop
http://jsperf.com/new-array-vs-splice-vs-slice/54

Closes #9942

ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js