fix[TagsView]: fixed click.middle can close affixed tag bug (#2649)

src/layout/components/TagsView/index.vue

@@ -9,16 +9,16 @@
         :to="{ path: tag.path, query: tag.query, fullPath: tag.fullPath }"
         tag="span"
         class="tags-view-item"
-        @click.middle.native="closeSelectedTag(tag)"
+        @click.middle.native="!isAffix(tag)?closeSelectedTag(tag):''"
         @contextmenu.prevent.native="openMenu(tag,$event)"
       >
         {{ tag.title }}
-        <span v-if="!tag.meta.affix" class="el-icon-close" @click.prevent.stop="closeSelectedTag(tag)" />
+        <span v-if="!isAffix(tag)" class="el-icon-close" @click.prevent.stop="closeSelectedTag(tag)" />
       </router-link>
     </scroll-pane>
     <ul v-show="visible" :style="{left:left+'px',top:top+'px'}" class="contextmenu">
       <li @click="refreshSelectedTag(selectedTag)">Refresh</li>
-      <li v-if="!(selectedTag.meta&&selectedTag.meta.affix)" @click="closeSelectedTag(selectedTag)">Close</li>
+      <li v-if="!isAffix(selectedTag)" @click="closeSelectedTag(selectedTag)">Close</li>
       <li @click="closeOthersTags">Close Others</li>
       <li @click="closeAllTags(selectedTag)">Close All</li>
     </ul>
@@ -69,6 +69,9 @@ export default {
     isActive(route) {
       return route.path === this.$route.path
     },
+    isAffix(tag) {
+      return tag.meta && tag.meta.affix
+    },
     filterAffixTags(routes, basePath = '/') {
       let tags = []
       routes.forEach(route => {