rootView.backgroundColor in AppDelegate.m is no longer white by default in 0.58.3

[kdenz]

Environment

React Native Environment Info:
    System:
      OS: macOS 10.14.2
      CPU: (8) x64 Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz
      Memory: 1.20 GB / 16.00 GB
      Shell: 3.2.57 - /bin/bash
    Binaries:
      Node: 10.14.2 - ~/.nvm/versions/node/v10.14.2/bin/node
      Yarn: 1.12.3 - /usr/local/bin/yarn
      npm: 6.6.0 - ~/.nvm/versions/node/v10.14.2/bin/npm
      Watchman: 4.7.0 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 12.1, macOS 10.14, tvOS 12.1, watchOS 5.1
      Android SDK:
        API Levels: 20, 22, 23, 24, 26, 27
        Build Tools: 23.0.1, 23.0.3, 24.0.0, 26.0.0, 26.0.1, 27.0.3
        System Images: android-22 | Google APIs Intel x86 Atom, android-27 | Google Play Intel x86 Atom, android-28 | Google APIs Intel x86 Atom
    IDEs:
      Android Studio: 3.1 AI-173.4720617
      Xcode: 10.1/10B61 - /usr/bin/xcodebuild
    npmPackages:
      react: 16.6.3 => 16.6.3 
      react-native: ^0.58.3 => 0.58.3 
    npmGlobalPackages:
      react-native-cli: 2.0.1
      react-native-git-upgrade: 0.2.7

Description

I'm not sure if this is regression.
Previously it's
rootView.backgroundColor = [[UIColor alloc] initWithRed:1.0f green:1.0f blue:1.0f alpha:1];
Which is white

And now it becomes rootView.backgroundColor = [UIColor blackColor];
Which makes it black, and this has broken stuff like
storybookjs/storybook#5377

I had to change
rootView.backgroundColor = [UIColor blackColor]; to
rootView.backgroundColor = [UIColor whiteColor]; in order to revert to the old behavior

Reproducible Demo

Simply initialize an app under 0.58.3 and you'll see default backgrounds becoming black instead of white
For me I upgraded from 0.57.x to 0.58.3 using react-native-git-upgrade

[kelset]

I had to change
rootView.backgroundColor = [UIColor blackColor]; to
rootView.backgroundColor = [UIColor whiteColor]; in order to revert to the old behavior

Can you maybe submit a PR that reintroduces this?

That way we'd have a change to see why it was changed in the first place. Or maybe look at the git history to see which commit changed it?