tweak

src/compiler/codegen/directives/model.js

@@ -53,7 +53,7 @@ function genDefaultModel (el, value, modifiers) {
     : `${value}=$event.target.value`
 
   if (needCompositionGuard) {
-    code = `if($event.target._composing)return;${code}`
+    code = `if($event.target.composing)return;${code}`
   }
   addHandler(el.events, event, code)
   el.props.push({

src/runtime/directives/model.js

@@ -24,11 +24,11 @@ export default {
 }
 
 function onCompositionStart (e) {
-  e.target._composing = true
+  e.target.composing = true
 }
 
 function onCompositionEnd (e) {
-  e.target._composing = false
+  e.target.composing = false
   trigger(e)
 }