Use Date.now when performance.now doesn't exist
Fix null placeholder issue
Fix vertical slider translation direction
Add active property to slider
Merge pull request #1244 from romancortes/vertical-slider

Fix vertical slider translation direction
Remove unnecessary setter for active in slider
Add tests for slider's active property
Merge pull request #1245 from romancortes/add-active-property-to-slider

Add active property to slider
Add ModalOverlay
Add dismissOnExternalInteraction property
Add Overlay and ModalOverlay blueprints
Extend component mock and add rootComponent mock
Extend dom mock

Add HTML dom node and createElement function.
Add hasModalMask property to ModalOverlay
Disable closing on external interaction on ModalOverlay
Add AbstractAlert
Add Confirm
Add AbstractAlert and AbstractConfirm blueprint
Fix abstract alert and confirm tests
Add OKButton and CancelButton constants