feat: v-on with no argument

packages/runtime-core/src/helpers/toHandlers.ts

@@ -0,0 +1,15 @@
+import { isObject } from '@vue/shared'
+import { warn } from '../warning'
+
+// For prefixing keys in v-on="obj" with "on"
+export function toHandlers(obj: Record<string, any>): Record<string, any> {
+  const ret: Record<string, any> = {}
+  if (__DEV__ && !isObject(obj)) {
+    warn(`v-on with no argument expects an object value.`)
+    return ret
+  }
+  for (const key in obj) {
+    ret[`on${key}`] = obj[key]
+  }
+  return ret
+}