Prevenitng redundant method calls on value property when initialized …

…with an empty string(master) (#3042)

* fix(date-picker): Prevenitng redundant method calls on value. #3021

* fix(date-picker): Changing the check for value property on selection. #3021

projects/igniteui-angular/src/lib/date-picker/date-picker.component.ts

@@ -599,7 +599,7 @@ export class IgxDatePickerComponent implements ControlValueAccessor, EditorProvi
      * @hidden
      */
     public handleSelection(date: Date) {
-        if (this.value !== null && this.value !== undefined) {
+        if (this.value) {
             date.setHours(this.value.getHours());
             date.setMinutes(this.value.getMinutes());
             date.setSeconds(this.value.getSeconds());