fix flow

flow/vnode.js

@@ -53,7 +53,6 @@ declare interface VNodeData {
   };
   directives?: Array<VNodeDirective>;
   keepAlive?: boolean;
-  [key: string]: any;
 }
 
 declare type VNodeDirective = {

src/core/instance/render.js

@@ -163,7 +163,7 @@ export function renderMixin (Vue: Class<Component>) {
         if (Array.isArray(value)) {
           value = toObject(value)
         }
-        const data = vnode.data
+        const data: any = vnode.data
         for (const key in value) {
           if (key === 'class' || key === 'style') {
             data[key] = value[key]