Add test to verify bug reported in issue vuejs#6918

Author: misoguy

test/unit/features/directives/model-dynamic.spec.js

@@ -40,6 +40,23 @@ describe('Directive v-model dynamic input type', () => {
     assertInputWorks(vm, chain).then(done)
   })
 
+  it('with v-else', done => {
+    const data = {
+      ok: true,
+      type: null,
+      test: 'b'
+    }
+    const vm = new Vue({
+      data,
+      template: `<div v-if="ok">haha</div><input v-else :type="type" v-model="test">`
+    }).$mount()
+    document.body.appendChild(vm.$el)
+    expect(vm.$el.textContent).toBe('haha')
+
+    vm.ok = false
+    assertInputWorks(vm).then(done)
+  })
+
   it('with v-for', done => {
     const vm = new Vue({
       data: {