fix(runtime-core): ensure raw slot function is only normalized once (vuejs#5358)

fix: vuejs#5343

Author: LinusBorg

packages/runtime-core/src/componentSlots.ts

@@ -63,6 +63,10 @@ const normalizeSlot = (
   rawSlot: Function,
   ctx: ComponentInternalInstance | null | undefined
 ): Slot => {
+  if ((rawSlot as any)._n) {
+    // already normalized - #5353
+    return rawSlot as Slot
+  }
   const normalized = withCtx((...args: any[]) => {
     if (__DEV__ && currentInstance) {
       warn(