Reset preventFocus after closing the popper with Escape. (#2147)

Return the preventFocus state to false after closing the calendar popper with Escape key. This issue prevented the calendar popper to open on the following navigations to the input with the keyboard.

src/index.jsx

@@ -688,14 +688,18 @@ export default class DatePicker extends React.Component {
       // stop the input from auto opening onFocus
       // close the popper
       // setFocus to the input
+      // allow input auto opening onFocus
       event.preventDefault();
       this.setState(
         {
           preventFocus: true
         },
         () => {
           this.setOpen(false);
-          setTimeout(this.setFocus); // return focus to the input
+          setTimeout(() => {
+            this.setFocus();
+            this.setState({ preventFocus: false });
+          });
         }
       );
     }

test/datepicker_test.js

@@ -136,6 +136,7 @@ describe("DatePicker", () => {
 
     defer(() => {
       expect(datePicker.calendar).to.not.exist;
+      expect(datePicker.state.preventFocus).to.be.false;
       expect(document.activeElement).to.equal(div.querySelector("input"));
       done();
     });