fix(types): make VNodeChildrenArrayContents type more accurate (vuejs#7287)

Author: ktsn

types/test/options-test.ts

@@ -1,4 +1,4 @@
-import Vue from "../index";
+import Vue, { VNode } from "../index";
 import { AsyncComponent, ComponentOptions, FunctionalComponentOptions } from "../index";
 import { CreateElement } from "../vue";
 
@@ -277,6 +277,19 @@ Vue.component('component-with-scoped-slot', {
   }
 })
 
+Vue.component('narrow-array-of-vnode-type', {
+  render (h): VNode {
+    const slot = this.$scopedSlots.default({})
+    if (typeof slot !== 'string') {
+      const first = slot[0]
+      if (!Array.isArray(first) && typeof first !== 'string') {
+        return first;
+      }
+    }
+    return h();
+  }
+})
+
 Vue.component('functional-component', {
   props: ['prop'],
   functional: true,

types/vnode.d.ts

@@ -3,9 +3,7 @@ import { Vue } from "./vue";
 export type ScopedSlot = (props: any) => VNodeChildrenArrayContents | string;
 
 export type VNodeChildren = VNodeChildrenArrayContents | [ScopedSlot] | string;
-export interface VNodeChildrenArrayContents {
-  [x: number]: VNode | string | VNodeChildren;
-}
+export interface VNodeChildrenArrayContents extends Array<VNode | string | VNodeChildrenArrayContents> {}
 
 export interface VNode {
   tag?: string;