Is this a bug report?

Yes.

Have you read the Bugs section of the How to Contribute guide?

Yes.

Environment

1. react-native -v: 1000.0.0 (master)
2. node -v: 8.1.2
3. npm -v: 5.0.3
4. yarn --version: N/A

Then, specify:

• Target Platform: Windows (react-native-windows)

• Development Operating System: Windows 10

• Build tools: Visual Studio

Steps to Reproduce

(Write your steps here:)

1. Add new native prop to RCTView native view manager in react-native-windows
2. Add prop to <View/> instance in JavaScript app / bundle
3. Exception that new prop is not a valid prop type (because it's not declared in ViewPropTypes)

Expected Behavior

I expect a way to extend ViewPropTypes for platform plugins to react-native.

Actual Behavior

There is no way to extend the ViewPropTypes for platform plugins.

I'll be filing a PR shortly.