Migrate ActivityIndicator to HostComponent

Summary:
NativeComponent as a type isn't needed now that we have HostComponent

Changelog:
[Internal]

Reviewed By: zackargyle, rickhanlonii

Differential Revision: D18873494

fbshipit-source-id: 5ba3fa25537f8249c80c2303dcdb380e3b6b0ac5

Libraries/Components/ActivityIndicator/ActivityIndicator.js

@@ -14,8 +14,7 @@ const Platform = require('../../Utilities/Platform');
 const React = require('react');
 const StyleSheet = require('../../StyleSheet/StyleSheet');
 const View = require('../View/View');
-
-import type {NativeComponent} from '../../Renderer/shims/ReactNative';
+import type {HostComponent} from '../../Renderer/shims/ReactNativeTypes';
 import type {ViewProps} from '../View/ViewPropTypes';
 
 const PlatformActivityIndicator =
@@ -118,7 +117,10 @@ const ActivityIndicator = (props: Props, forwardedRef?: any) => {
   );
 };
 
-const ActivityIndicatorWithRef = React.forwardRef(ActivityIndicator);
+const ActivityIndicatorWithRef: React.AbstractComponent<
+  Props,
+  HostComponent<mixed>,
+> = React.forwardRef(ActivityIndicator);
 ActivityIndicatorWithRef.displayName = 'ActivityIndicator';
 
 /* $FlowFixMe(>=0.89.0 site=react_native_fb) This comment suppresses an error
@@ -146,7 +148,4 @@ const styles = StyleSheet.create({
   },
 });
 
-/* $FlowFixMe(>=0.89.0 site=react_native_fb) This comment suppresses an error
- * found when Flow v0.89 was deployed. To see the error, delete this comment
- * and run Flow. */
-module.exports = (ActivityIndicatorWithRef: Class<NativeComponent<Props>>);
+module.exports = ActivityIndicatorWithRef;