[Improvement] Tab: click event add title param (#761)

test/components/tabs.vue

@@ -4,8 +4,8 @@
     :duration="duration"
     :sticky="sticky"
     :swipeable="swipeable"
-    @click="handleTabClick"
-    @disabled="handleTabDisabledClick"
+    @click="$emit('click')"
+    @disabled="$emit('disabled')"
   >
     <van-tab :title="firstTabTitle" :disabled="firstTabDisabled">内容一</van-tab>
     <van-tab title="选项二">内容二</van-tab>
@@ -33,15 +33,6 @@ export default {
       active: 0,
       duration: 0.5
     };
-  },
-
-  methods: {
-    handleTabClick(index) {
-      this.$emit('click');
-    },
-    handleTabDisabledClick(index) {
-      this.$emit('disabled');
-    }
   }
 };
 </script>