Use ng-repeat with track by to prevent dupes and improve performance

[andrewboni]

• Prevents ng-repeat dupes error
• Improve ng-repeat performance

[yoavaa]

I have checked the commit, but some tests are failing - specifically regarding filtering

[melnikaite]

track by should be placed after all filters
ng-repeat="node in node.{{options.nodeChildren}} | filter:filterExpression:filterComparator {{options.orderBy}} track by $index"

[valikonen]

But where we must put this track by $index. I've try to add into template directly and is translated like:

The template it looks like:
'<li ng-repeat="node in node.' + $scope.options.nodeChildren + ' | filter:filterExpression:filterComparator ' + orderBy + '" ng-class="headClass(node)" track by $index '+classIfDefined($scope.options.injectClasses.li, true)+'>' +