feat(AbstractDropdownView): add blur event to view spec

Author: cal-smith

src/dropdown/abstract-dropdown-view.class.ts

@@ -19,6 +19,17 @@ export class AbstractDropdownView {
 	 * Emits selection events to other class.
 	 */
 	@Output() select: EventEmitter<Object>;
+	/**
+	 * Event to suggest a blur on the view.
+	 * Emits _after_ the first/last item has been focussed
+	 * ex.
+	 * ArrowUp -> focus first item
+	 * ArrowUp -> emit event
+	 *
+	 * It's recommended that the implementing view include a specific type union of possible blurs
+	 * ex. `@Output() blur = new EventEmitter<"top" | "bottom">();`
+	 */
+	@Output() blur: EventEmitter<any>;
 	/**
 	 * Specifies whether or not the `DropdownList` supports selecting multiple items as opposed to single
 	 * item selection.