fix-Firefox (#6359)

Author: HiWangyeah

src/core/util/env.js

@@ -17,7 +17,7 @@ export const isAndroid = UA && UA.indexOf('android') > 0
 export const isIOS = UA && /iphone|ipad|ipod|ios/.test(UA)
 export const isChrome = UA && /chrome\/\d+/.test(UA) && !isEdge
 
-// Firefix has a "watch" function on Object.prototype...
+// Firefox has a "watch" function on Object.prototype...
 export const nativeWatch = ({}).watch
 
 export let supportsPassive = false