types: Pass exact object as second argument of $Diff wherever we us…

…e it.

An instance of zulip#3452.

src/actionTypes.js

@@ -305,7 +305,7 @@ type GenericEventAction = {|
 |};
 
 type EventNewMessageAction = {|
-  ...$Diff<MessageEvent, { flags: mixed }>,
+  ...$Diff<MessageEvent, {| flags: mixed |}>,
   type: typeof EVENT_NEW_MESSAGE,
   caughtUp: CaughtUpState,
   ownUserId: UserId,

src/common/InputWithClearButton.js

@@ -14,7 +14,7 @@ const componentStyles = createStyleSheet({
   },
 });
 
-type Props = $ReadOnly<$Diff<InputProps, { textInputRef: mixed, value: mixed, _: mixed }>>;
+type Props = $ReadOnly<$Diff<InputProps, {| textInputRef: mixed, value: mixed, _: mixed |}>>;
 
 type State = {|
   canBeCleared: boolean,

src/common/PasswordInput.js

@@ -27,7 +27,7 @@ const styles = createStyleSheet({
 type Props = $ReadOnly<$Diff<InputProps,
   // "mixed" here is a way of spelling "no matter *what* type
   // `InputProps` allows for these, don't allow them here."
-  { secureTextEntry: mixed, autoCorrect: mixed, autoCapitalize: mixed, _: mixed }>>;
+  {| secureTextEntry: mixed, autoCorrect: mixed, autoCapitalize: mixed, _: mixed |}>>;
 
 type State = {|
   isHidden: boolean,

src/message/__tests__/fetchActions-test.js

@@ -118,7 +118,7 @@ describe('fetchActions', () => {
     };
     const message1 = eg.streamMessage({ id: 1, sender });
 
-    type CommonFields = $Diff<Message, { reactions: mixed, avatar_url: mixed }>;
+    type CommonFields = $Diff<Message, {| reactions: mixed, avatar_url: mixed |}>;
 
     // message1 exactly as we receive it from the server, before our
     // own transformations.

src/types.js

@@ -110,7 +110,7 @@ export type Account = {|
  * Use `identityOfAuth` or `identityOfAccount` to make one of these where
  * you have an `Auth` or `Account`.
  */
-export type Identity = $Diff<Auth, { apiKey: string }>;
+export type Identity = $Diff<Auth, {| apiKey: string |}>;
 
 export type EmojiType = 'image' | 'unicode';
 

src/users/UserItem.js

@@ -100,7 +100,7 @@ export class UserItemRaw<
 }
 
 type OuterProps = $ReadOnly<{|
-  ...$Exact<$Diff<ElementConfig<typeof UserItemRaw>, { user: mixed }>>,
+  ...$Exact<$Diff<ElementConfig<typeof UserItemRaw>, {| user: mixed |}>>,
   userId: UserId,
 |}>;
 

src/webview/js/js.js

@@ -588,7 +588,7 @@ export const handleInitialLoad = (
   scrollMessageId: number | null,
   // The `realm` part of an `Auth` object is a URL object. It's passed
   // in its stringified form.
-  rawAuth: {| ...$Diff<Auth, { realm: mixed }>, realm: string |},
+  rawAuth: {| ...$Diff<Auth, {| realm: mixed |}>, realm: string |},
 ) => {
   const auth: Auth = { ...rawAuth, realm: new URL(rawAuth.realm) };