[iOS] TextInput clear button is not accessible

Is this a bug report?

Yes

Have you read the Contributing Guidelines?

Yes

Environment

Environment:
OS: macOS High Sierra 10.13.1
Node: 6.12.0
Yarn: 1.3.2
npm: 5.5.1
Watchman: 4.7.0
Xcode: Xcode 9.1 Build version 9B55
Android Studio: 3.0 AI-171.4408382

Packages: (wanted => installed)
react: 16.0.0-beta.5 => 16.0.0-beta.5
react-native: ^0.49.5 => 0.49.5

Target Platform: iOS (9)

Steps to Reproduce

https://snack.expo.io/S1EkFy5gG

1. Input any text for the clear button to appear.
2. Turn on Voice Over
3. Try to select the clear button.

Expected Behavior

"Clear" button can be selected and activated. iOS native text input control supports it.

Actual Behavior

Voice Over cannot focus on the "clear" button.

Reproducible Demo

https://snack.expo.io/S1EkFy5gG