fix: always install composition event listeners

Previously the installation was skipped on Android because
it was not needed for Chinese IME - however some IMEs such
as Japanese exhibits the same behavior as on other browers.

So it is safer to always enable the check. Closes vuejs#7367

src/platforms/web/runtime/directives/model.js

@@ -6,7 +6,7 @@
 import { isTextInputType } from 'web/util/element'
 import { looseEqual, looseIndexOf } from 'shared/util'
 import { mergeVNodeHook } from 'core/vdom/helpers/index'
-import { warn, isAndroid, isIE9, isIE, isEdge } from 'core/util/index'
+import { warn, isIE9, isIE, isEdge } from 'core/util/index'
 
 /* istanbul ignore if */
 if (isIE9) {
@@ -34,15 +34,13 @@ const directive = {
     } else if (vnode.tag === 'textarea' || isTextInputType(el.type)) {
       el._vModifiers = binding.modifiers
       if (!binding.modifiers.lazy) {
+        el.addEventListener('compositionstart', onCompositionStart)
+        el.addEventListener('compositionend', onCompositionEnd)
         // Safari < 10.2 & UIWebView doesn't fire compositionend when
         // switching focus before confirming composition choice
         // this also fixes the issue where some browsers e.g. iOS Chrome
         // fires "change" instead of "input" on autocomplete.
         el.addEventListener('change', onCompositionEnd)
-        if (!isAndroid) {
-          el.addEventListener('compositionstart', onCompositionStart)
-          el.addEventListener('compositionend', onCompositionEnd)
-        }
         /* istanbul ignore if */
         if (isIE9) {
           el.vmodel = true

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

@@ -183,27 +183,25 @@ describe('Directive v-model text', () => {
     })
   }
 
-  if (!isAndroid) {
-    it('compositionevents', function (done) {
-      const vm = new Vue({
-        data: {
-          test: 'foo'
-        },
-        template: '<input v-model="test">'
-      }).$mount()
-      const input = vm.$el
-      triggerEvent(input, 'compositionstart')
-      input.value = 'baz'
-      // input before composition unlock should not call set
-      triggerEvent(input, 'input')
-      expect(vm.test).toBe('foo')
-      // after composition unlock it should work
-      triggerEvent(input, 'compositionend')
-      triggerEvent(input, 'input')
-      expect(vm.test).toBe('baz')
-      done()
-    })
-  }
+  it('compositionevents', function (done) {
+    const vm = new Vue({
+      data: {
+        test: 'foo'
+      },
+      template: '<input v-model="test">'
+    }).$mount()
+    const input = vm.$el
+    triggerEvent(input, 'compositionstart')
+    input.value = 'baz'
+    // input before composition unlock should not call set
+    triggerEvent(input, 'input')
+    expect(vm.test).toBe('foo')
+    // after composition unlock it should work
+    triggerEvent(input, 'compositionend')
+    triggerEvent(input, 'input')
+    expect(vm.test).toBe('baz')
+    done()
+  })
 
   it('warn invalid tag', () => {
     new Vue({