Merge pull request #31492 from nadiia/0.65-stable-roottag-context

[AppContainer] Add back legacy rootTag childContex

Libraries/ReactNative/AppContainer.js

@@ -14,8 +14,11 @@ import StyleSheet from '../StyleSheet/StyleSheet';
 import {type EventSubscription} from '../vendor/emitter/EventEmitter';
 import {RootTagContext, createRootTag} from './RootTag';
 import type {RootTag} from './RootTag';
+import PropTypes from 'prop-types';
 import * as React from 'react';
 
+type Context = {rootTag: number | RootTag, ...};
+
 type Props = $ReadOnly<{|
   children?: React.Node,
   fabric?: boolean,
@@ -43,6 +46,18 @@ class AppContainer extends React.Component<Props, State> {
 
   static getDerivedStateFromError: any = undefined;
 
+  static childContextTypes:
+    | any
+    | {|rootTag: React$PropType$Primitive<number>|} = {
+    rootTag: PropTypes.number,
+  };
+
+  getChildContext(): Context {
+    return {
+      rootTag: this.props.rootTag,
+    };
+  }
+
   componentDidMount(): void {
     if (__DEV__) {
       if (!global.__RCTProfileIsProfiling) {