Fixes to non-product code (e.g React Native)

Summary:
We are working on making the empty object literal `{}` have the type `{}` - i.e. exact empty object - rather than being unsealed.

Some manual fixes, in particular to React Native code, which is used and can be synced to other repos (e.g. WWW).

With these changes, error diff in Xplat is down to ~1990 errors

Note that after I roll out `exact_empty_objects`, I'll codemod all the `{...null}` (the only way to get an exact empty object currently) back to `{}`

Changelog: [Internal]

Reviewed By: SamChou19815

Differential Revision: D36142838

fbshipit-source-id: 054caf370db230f42a4c5f5706c88979ef246537

Libraries/Animated/nodes/AnimatedStyle.js

@@ -23,7 +23,7 @@ class AnimatedStyle extends AnimatedWithChildren {
 
   constructor(style: any) {
     super();
-    style = flattenStyle(style) || {};
+    style = flattenStyle(style) || ({}: {[string]: any});
     if (style.transform) {
       style = {
         ...style,

Libraries/Components/TextInput/TextInput.js

@@ -976,7 +976,7 @@ function InternalTextInput(props: Props): React.Node {
   // that the update should be ignored and we should stick with the value
   // that we have in JS.
   useLayoutEffect(() => {
-    const nativeUpdate = {};
+    const nativeUpdate: {text?: string, selection?: Selection} = {...null};
 
     if (lastNativeText !== props.value && typeof props.value === 'string') {
       nativeUpdate.text = props.value;

Libraries/Core/setUpPerformance.js

@@ -11,7 +11,7 @@
 'use strict';
 
 if (!global.performance) {
-  global.performance = {};
+  global.performance = ({...null}: {now?: () => number});
 }
 
 /**

Libraries/Image/ImageSource.js

@@ -91,9 +91,7 @@ export type ImageSource =
   | ImageURISource
   | $ReadOnlyArray<ImageURISource>;
 
-export function getImageSourceProperties(
-  imageSource: ImageURISource,
-): $ReadOnly<{
+type ImageSourceProperties = {
   body?: ?string,
   bundle?: ?string,
   cache?: ?('default' | 'reload' | 'force-cache' | 'only-if-cached'),
@@ -104,8 +102,12 @@ export function getImageSourceProperties(
   uri?: ?string,
   width?: ?number,
   ...
-}> {
-  const object = {};
+};
+
+export function getImageSourceProperties(
+  imageSource: ImageURISource,
+): $ReadOnly<ImageSourceProperties> {
+  const object: ImageSourceProperties = {};
   if (imageSource.body != null) {
     object.body = imageSource.body;
   }

Libraries/Lists/VirtualizedList.js

@@ -1205,7 +1205,7 @@ class VirtualizedList extends React.PureComponent<Props, State> {
   _hasDoneInitialScroll = false;
   _hasInteracted = false;
   _hasMore = false;
-  _hasWarned = {};
+  _hasWarned: {[string]: boolean} = {};
   _headerLength = 0;
   _hiPriInProgress: boolean = false; // flag to prevent infinite hiPri cell limit update
   _highestMeasuredFrameIndex = 0;

Libraries/Utilities/stringifySafe.js

@@ -65,7 +65,7 @@ export function createStringifySafeWithLimits(limits: {|
         retval = `{ ... object with ${keys.length} keys ... }`;
       } else if (keys.length > maxObjectKeysLimit) {
         // Return a sample of the keys.
-        retval = {};
+        retval = ({}: {[string]: mixed});
         for (let k of keys.slice(0, maxObjectKeysLimit)) {
           retval[k] = value[k];
         }

Libraries/WebSocket/WebSocket.js

@@ -101,9 +101,10 @@ class WebSocket extends (EventTarget(...WEBSOCKET_EVENTS): any) {
       protocols = [protocols];
     }
 
-    const {headers = {}, ...unrecognized} = options || {};
+    const {headers = {}, ...unrecognized} = options || {...null};
 
     // Preserve deprecated backwards compatibility for the 'origin' option
+    // $FlowFixMe[prop-missing]
     if (unrecognized && typeof unrecognized.origin === 'string') {
       console.warn(
         'Specifying `origin` as a WebSocket connection option is deprecated. Include it under `headers` instead.',

packages/rn-tester/js/components/RNTesterPage.js

@@ -23,7 +23,11 @@ type Props = $ReadOnly<{|
 class RNTesterPage extends React.Component<Props> {
   render(): React.Node {
     let ContentWrapper;
-    let wrapperProps = {};
+    let wrapperProps: {
+      automaticallyAdjustContentInsets?: boolean,
+      keyboardShouldPersistTaps?: string,
+      keyboardDismissMode?: string,
+    } = {...null};
     if (this.props.noScroll) {
       ContentWrapper = ((View: any): React.ComponentType<any>);
     } else {

packages/rn-tester/js/examples/Crash/CrashExample.js

@@ -26,7 +26,9 @@ exports.examples = [
         <Button
           title="JS crash"
           onPress={() => {
-            const a = {};
+            const a = {...null};
+            // $FlowIgnore[prop-missing]
+            // $FlowIgnore[incompatible-use]
             const b = a.w.q; // js crash here
             console.log(b);
           }}