[new feature] Tabbar: add active-color prop (#2372)

packages/tabbar-item/index.vue

@@ -1,6 +1,7 @@
 <template>
   <div
     :class="b({ active })"
+    :style="style"
     @click="onClick"
   >
     <div :class="b('icon', { dot })">
@@ -47,6 +48,12 @@ export default create({
     };
   },
 
+  computed: {
+    style() {
+      return this.active ? { color: this.$parent.activeColor } : null;
+    }
+  },
+
   beforeCreate() {
     this.$parent.items.push(this);
   },