fix(selection.js): getSelectedRows will work on primitive data types.
fix(selection.js): getSelectedRows will work on primitive data types.

Ensuring that the presence of $$hashKey is only needed for non-objects.

fix #6704

angular-ui/ng-grid,angular-ui/ui-grid,angular-ui/ng-grid,angular-ui/ui-grid,angular-ui/ng-grid,angular-ui/ui-grid