dillon1000/react

Replace object getter with `Object.defineProperty` in TestRenderer (#10473)

* Add babel transform for object getters

**what is the change?:**
We were not transforming object getters[1], and our new TestRenderer
uses one.[2]

[1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/get
[2]: https://github.com/facebook/react/blob/master/src/renderers/testing/ReactTestRendererFiberEntry.js#L569

**why make this change?:**
Our internal build system was not supporting object getters.

**test plan:**
`yarn build && yarn test`
Also built and opened the 'packaging' fixture.

Honestly I'm not sure what else to test, this seems pretty low risk.

**issue:**
None opened yet

* Replace object getter with `Object.defineProperty` in TestRenderer

**what is the change?:**
Replaces an Object Getter [1] with `Object.defineProperty`.

[1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/get

**why make this change?:**
Our internal build system does not support object getters.

**test plan:**
We should do follow-up work to ensure that this doesn't come up again -
we can't commit code which uses object getters.

**issue:**
No issue opened yet

* Tweak the Object.defineProperty call in test renderer to make flow pass

**what is the change?:**
- switched from `Object.defineProperties` to `Object.defineProperty`
- set some undefined properties to get flow to pass

**why make this change?:**
- Flow doesn't seem to play nicely with `Object.defineProperty/ies`
  calls, specifically when you implement `get` and `set` methods.
  See https://github.com/facebook/flow/issues/1336
- Switched from `properties` to `property` because it seems more
  conventional in our codebase to use `property`, and I'm only setting
  one anyway.

**test plan:**
`flow`

**issue:**
no issue

* More flow type tweaking

**what is the change?:**
Forced the typing of an argument to 'Object.defineProperty' to be
'Object' to avoid an issue with Flow.

**why make this change?:**
To get tests passing and flow passing.

**test plan:**
`flow && yarn test`

**issue:**