Tightening type for flattenStyle

Reviewed By: yungsters

Differential Revision: D7131703

fbshipit-source-id: d8e37fcd0c743057e04760b1e50f8d879bd2826a

Author: elicwhite

Libraries/Animated/src/nodes/AnimatedTransform.js

@@ -15,9 +15,9 @@ const AnimatedWithChildren = require('./AnimatedWithChildren');
 const NativeAnimatedHelper = require('../NativeAnimatedHelper');
 
 class AnimatedTransform extends AnimatedWithChildren {
-  _transforms: Array<Object>;
+  _transforms: $ReadOnlyArray<Object>;
 
-  constructor(transforms: Array<Object>) {
+  constructor(transforms: $ReadOnlyArray<Object>) {
     super();
     this._transforms = transforms;
   }
@@ -34,7 +34,7 @@ class AnimatedTransform extends AnimatedWithChildren {
     });
   }
 
-  __getValue(): Array<Object> {
+  __getValue(): $ReadOnlyArray<Object> {
     return this._transforms.map(transform => {
       const result = {};
       for (const key in transform) {
@@ -49,7 +49,7 @@ class AnimatedTransform extends AnimatedWithChildren {
     });
   }
 
-  __getAnimatedValue(): Array<Object> {
+  __getAnimatedValue(): $ReadOnlyArray<Object> {
     return this._transforms.map(transform => {
       const result = {};
       for (const key in transform) {

Libraries/StyleSheet/flattenStyle.js

@@ -9,10 +9,9 @@
  */
 'use strict';
 
-var invariant = require('fbjs/lib/invariant');
 var ReactNativePropRegistry;
 
-import type { StyleObj } from 'StyleSheetTypes';
+import type { DimensionValue, ColorValue, StyleProp, Style } from 'StyleSheetTypes';
 
 function getStyle(style) {
   if (ReactNativePropRegistry === undefined) {
@@ -24,11 +23,10 @@ function getStyle(style) {
   return style;
 }
 
-function flattenStyle(style: ?StyleObj): ?Object {
-  if (!style) {
+function flattenStyle(style: ?StyleProp<Style<DimensionValue, ColorValue>>): ?Style<DimensionValue, ColorValue> {
+  if (style == null) {
     return undefined;
   }
-  invariant(style !== true, 'style may be false but not true');
 
   if (!Array.isArray(style)) {
     /* $FlowFixMe(>=0.63.0 site=react_native_fb) This comment suppresses an