fix(ssr): handle fallthrough attrs in ssr compile output

packages/runtime-core/src/componentOptions.ts

@@ -119,7 +119,8 @@ export interface ComponentOptionsBase<
   ssrRender?: (
     ctx: any,
     push: (item: any) => void,
-    parentInstance: ComponentInternalInstance
+    parentInstance: ComponentInternalInstance,
+    attrs?: Data
   ) => void
 
   /**

packages/runtime-core/src/vnode.ts

@@ -554,8 +554,7 @@ export function normalizeChildren(vnode: VNode, children: unknown) {
 const handlersRE = /^on|^vnode/
 
 export function mergeProps(...args: (Data & VNodeProps)[]) {
-  const ret: Data = {}
-  extend(ret, args[0])
+  const ret = extend({}, args[0])
   for (let i = 1; i < args.length; i++) {
     const toMerge = args[i]
     for (const key in toMerge) {