Remove use of flatten where possible (#9325)

* remove use of flatten where possible

* restore flatten where it says it's needed

* missing utils alpha

src/screens/Messages/components/MessageInput.web.tsx

@@ -1,5 +1,5 @@
 import React from 'react'
-import {Pressable, StyleSheet, View} from 'react-native'
+import {Pressable, View} from 'react-native'
 import {msg} from '@lingui/macro'
 import {useLingui} from '@lingui/react'
 import Graphemer from 'graphemer'
@@ -19,7 +19,7 @@ import {
   type EmojiPickerPosition,
 } from '#/view/com/composer/text-input/web/EmojiPicker'
 import * as Toast from '#/view/com/util/Toast'
-import {atoms as a, useTheme} from '#/alf'
+import {atoms as a, flatten, useTheme} from '#/alf'
 import {Button} from '#/components/Button'
 import {useSharedInputStyles} from '#/components/forms/TextField'
 import {EmojiArc_Stroke2_Corner0_Rounded as EmojiSmile} from '#/components/icons/Emoji'
@@ -199,7 +199,7 @@ export function MessageInput({
         </Button>
         <TextareaAutosize
           ref={textAreaRef}
-          style={StyleSheet.flatten([
+          style={flatten([
             a.flex_1,
             a.px_sm,
             a.border_0,