composebox: Use SafeAreaView in ComposeBox

Fixes zulip#3066

Previous approach almost worked correctly, but there was one
case it didn't - when the keyboard did pop on an iPhone, the
bottom space was sill there, though it shouldn't, as the keyboard
is located over the `Home Indicator`.

src/compose/ComposeBox.js

@@ -12,7 +12,6 @@ import type {
   InputSelection,
   UserOrBot,
   Dispatch,
-  Dimensions,
 } from '../types';
 import { connect } from '../react-redux';
 import {
@@ -50,7 +49,6 @@ import AutocompleteView from '../autocomplete/AutocompleteView';
 type SelectorProps = {|
   auth: Auth,
   usersByEmail: Map<string, UserOrBot>,
-  safeAreaInsets: Dimensions,
   isAdmin: boolean,
   isAnnouncementOnly: boolean,
   isSubscribed: boolean,
@@ -317,7 +315,6 @@ class ComposeBox extends PureComponent<Props, State> {
       narrow,
       usersByEmail,
       editMessage,
-      safeAreaInsets,
       isAdmin,
       isAnnouncementOnly,
       isSubscribed,
@@ -331,7 +328,6 @@ class ComposeBox extends PureComponent<Props, State> {
 
     const placeholder = getComposeInputPlaceholder(narrow, auth.email, usersByEmail);
     const style = {
-      paddingBottom: safeAreaInsets.bottom,
       backgroundColor: 'rgba(127, 127, 127, 0.1)',
     };
 
@@ -406,7 +402,6 @@ class ComposeBox extends PureComponent<Props, State> {
 export default connect((state, props): SelectorProps => ({
   auth: getAuth(state),
   usersByEmail: getActiveUsersByEmail(state),
-  safeAreaInsets: getSession(state).safeAreaInsets,
   isAdmin: getIsAdmin(state),
   isAnnouncementOnly: getIsActiveStreamAnnouncementOnly(state, props.narrow),
   isSubscribed: getIsActiveStreamSubscribed(state, props.narrow),