Clear title field on drawer close

Clear Requirement Title input field on drawer close to
prevent having stale title on next drawer open.

ee/app/assets/javascripts/requirements/components/requirement_form.vue

@@ -62,6 +62,12 @@ export default {
       },
       deep: true,
     },
+    drawerOpen(value) {
+      // Clear `title` value on drawer close.
+      if (!value) {
+        this.title = '';
+      }
+    },
   },
   methods: {
     getDrawerHeaderHeight() {

ee/spec/frontend/requirements/components/requirement_form_spec.js

@@ -114,6 +114,22 @@ describe('RequirementForm', () => {
         expect(wrapperWithRequirement.vm.title).toBe('');
       });
     });
+
+    describe('drawerOpen', () => {
+      it('clears `title` value when `drawerOpen` prop is changed to false', async () => {
+        wrapper.setData({
+          title: 'Foo',
+        });
+
+        wrapper.setProps({
+          drawerOpen: false,
+        });
+
+        await wrapper.vm.$nextTick();
+
+        expect(wrapper.vm.title).toBe('');
+      });
+    });
   });
 
   describe('methods', () => {