fix transition appear class fallback (fix #4985)

src/platforms/web/runtime/modules/transition.js

@@ -68,9 +68,9 @@ export function enter (vnode: VNodeWithData, toggleDisplay: ?() => void) {
     return
   }
 
-  const startClass = isAppear ? appearClass : enterClass
-  const activeClass = isAppear ? appearActiveClass : enterActiveClass
-  const toClass = isAppear ? appearToClass : enterToClass
+  const startClass = isAppear && appearClass ? appearClass : enterClass
+  const activeClass = isAppear && appearActiveClass ? appearActiveClass : enterActiveClass
+  const toClass = isAppear && appearToClass ? appearToClass : enterToClass
 
   const beforeEnterHook = isAppear ? (beforeAppear || beforeEnter) : beforeEnter
   const enterHook = isAppear ? (typeof appear === 'function' ? appear : enter) : enter

src/platforms/web/runtime/transition-util.js

@@ -24,14 +24,11 @@ export function resolveTransition (def?: string | Object): ?Object {
 const autoCssTransition: (name: string) => Object = cached(name => {
   return {
     enterClass: `${name}-enter`,
-    leaveClass: `${name}-leave`,
-    appearClass: `${name}-enter`,
     enterToClass: `${name}-enter-to`,
-    leaveToClass: `${name}-leave-to`,
-    appearToClass: `${name}-enter-to`,
     enterActiveClass: `${name}-enter-active`,
-    leaveActiveClass: `${name}-leave-active`,
-    appearActiveClass: `${name}-enter-active`
+    leaveClass: `${name}-leave`,
+    leaveToClass: `${name}-leave-to`,
+    leaveActiveClass: `${name}-leave-active`
   }
 })