fix(v-model/emit): update:camelCase events should trigger kebab case equivalent

close #656

packages/runtime-core/src/component.ts

@@ -25,7 +25,8 @@ import {
   NO,
   makeMap,
   isPromise,
-  isArray
+  isArray,
+  hyphenate
 } from '@vue/shared'
 import { SuspenseBoundary } from './components/Suspense'
 import { CompilerOptions } from '@vue/compiler-core'
@@ -221,7 +222,11 @@ export function defineComponentInstance(
 
     emit: (event, ...args): any[] => {
       const props = instance.vnode.props || EMPTY_OBJ
-      const handler = props[`on${event}`] || props[`on${capitalize(event)}`]
+      let handler = props[`on${event}`] || props[`on${capitalize(event)}`]
+      if (!handler && event.indexOf('update:') === 0) {
+        event = hyphenate(event)
+        handler = props[`on${event}`] || props[`on${capitalize(event)}`]
+      }
       if (handler) {
         const res = callWithAsyncErrorHandling(
           handler,