Add config to toggle StrictMode (#7035)

config/default-disco.js

@@ -23,6 +23,7 @@ module.exports = {
     'discoParamsToUse',
     'enableDevTools',
     'enableRequestID',
+    'enableStrictMode',
     'experiments',
     'hctEnabled',
     'hrefLangsMap',

config/default.js

@@ -50,6 +50,8 @@ module.exports = {
   // If true node will serve the static files.
   enableNodeStatics: false,
 
+  enableStrictMode: true,
+
   isDeployed: true,
   isDevelopment: false,
 
@@ -112,6 +114,7 @@ module.exports = {
     'enableFeatureHomeHeroGuides',
     'enableFeatureStaticThemesForAndroid',
     'enableRequestID',
+    'enableStrictMode',
     'experiments',
     'fxaConfig',
     'hctEnabled',

src/core/components/Root/index.js

@@ -3,27 +3,40 @@ import * as React from 'react';
 import { ConnectedRouter } from 'connected-react-router';
 import { CookiesProvider, Cookies } from 'react-cookie';
 import { Provider } from 'react-redux';
+import config from 'config';
 
 import I18nProvider from 'core/i18n/Provider';
 import type { I18nType } from 'core/types/i18n';
 import type { ReduxStore } from 'core/types/redux';
 import type { ReactRouterHistoryType } from 'core/types/router';
 
 type Props = {|
+  _config?: typeof config,
   children: React.Node,
   cookies?: typeof Cookies,
   history: ReactRouterHistoryType,
   i18n: I18nType,
   store: ReduxStore,
 |};
 
-const Root = ({ children, history, i18n, store, cookies = null }: Props) => (
+const Root = ({
+  _config = config,
+  children,
+  history,
+  i18n,
+  store,
+  cookies = null,
+}: Props) => (
   <I18nProvider i18n={i18n}>
     <Provider store={store} key="provider">
       <ConnectedRouter history={history}>
         <CookiesProvider cookies={cookies}>
           {/* $FLOW_FIXME: https://github.com/facebook/react/issues/12553 */}
-          <React.StrictMode>{children}</React.StrictMode>
+          {_config.get('enableStrictMode') ? (
+            <React.StrictMode>{children}</React.StrictMode>
+          ) : (
+            children
+          )}
         </CookiesProvider>
       </ConnectedRouter>
     </Provider>