Is this a bug report?

Yes

Have you read the Contributing Guidelines?

Yes

Environment

Environment:
OS: macOS High Sierra 10.13.4
Node: 8.4.0
Yarn: 1.6.0
npm: 5.4.2
Watchman: 4.9.0
Xcode: Xcode 9.3 Build version 9E145
Android Studio: 3.0 AI-171.4443003

Packages: (wanted => installed)
react: 16.3.0-alpha.1 => 16.3.0-alpha.1
react-native: https://github.com/expo/react-native/archive/sdk-26.0.0.tar.gz => 0.54.2

Steps to Reproduce

1. Place a TextInput
2. Set placeholder prop
3. Set allowFontScaling=false
4. On Android, go to Settings-> Accessibility and turn on "Large Text" (this varies a bit depending on the phone - the "Large Text" setting is there on stock Android, but Galaxy S phones have a "Visual" submenu under Accessibility and offer a slider for changing to all sorts of sizes).
5. Run the app on Android. Look at the placeholder and type something in the TextInput.

Expected Behavior

The TextInput's text and placeholder should be the same size when "Large Text" is turned on and when it is turned off.

Actual Behavior

The TextInput's text and placeholder is larger when "Large Text" is turned on, despite allowFontScaling=false.

Reproducible Demo

I have created a Snack demonstrating the issue here: https://snack.expo.io/@llamaluvr/android-textinput-allowfontscaling-not-respected

NOTE: This was originally opened and closed under (#13944). Opening a new issue with a demo and more detailed information.