wip: compat test coverage

packages/runtime-core/src/compat/renderFn.ts

@@ -113,7 +113,7 @@ export function compatH(
 ): VNode
 export function compatH(
   type: string | Component,
-  props?: LegacyVNodeProps,
+  props?: Data & LegacyVNodeProps,
   children?: LegacyVNodeChildren
 ): VNode
 
@@ -190,16 +190,12 @@ function convertLegacyProps(
     } else if (key === 'on' || key === 'nativeOn') {
       const listeners = legacyProps[key]
       for (const event in listeners) {
-        const handlerKey = convertLegacyEventKey(event)
+        let handlerKey = convertLegacyEventKey(event)
+        if (key === 'nativeOn') handlerKey += `Native`
         const existing = converted[handlerKey]
         const incoming = listeners[event]
         if (existing !== incoming) {
           if (existing) {
-            // for the rare case where the same handler is attached
-            // twice with/without .native modifier...
-            if (key === 'nativeOn' && String(existing) === String(incoming)) {
-              continue
-            }
             converted[handlerKey] = [].concat(existing as any, incoming as any)
           } else {
             converted[handlerKey] = incoming
@@ -307,6 +303,7 @@ function convertLegacySlots(vnode: VNode): VNode {
 }
 
 export function defineLegacyVNodeProperties(vnode: VNode) {
+  /* istanbul ignore if */
   if (
     isCompatEnabled(
       DeprecationTypes.RENDER_FUNCTION,