fix(ComboBox): fix lost change in state (#5784)
fix(ComboBox): fix lost change in state (#5784)

This change brings back the change detection logic of `selectedItems`
that was lost by moving away from `componentWillReceiveProps()`.

Fixes #5623.
carbon-design-system/carbon-components,carbon-design-system/carbon-components,carbon-design-system/carbon-components