remove unnecessary method

Author: yyx990803

src/util/push-state.js

@@ -37,10 +37,6 @@ export function setStateKey (key: string) {
   _key = key
 }
 
-export function genNewKey () {
-  _key = genKey()
-}
-
 export function pushState (url?: string, replace?: boolean) {
   // try...catch the pushState call to get around Safari
   // DOM Exception 18 where it limits to 100 pushState calls