Fix react-dom ReferenceError requestAnimationFrame in non-browser env (…

…facebook#13000)

The facebook#12931 ( facebook@79a740c ) broke the server-side rendering: in the `fixtures/ssr` the following error appeared from the server-side when `localhost:3000` is requested:
```
ReferenceError: requestAnimationFrame is not defined
    at /__CENSORED__/react/build/node_modules/react-dom/cjs/react-dom.development.js:5232:34
    at Object.<anonymous> (/__CENSORED__/react/build/node_modules/react-dom/cjs/react-dom.development.js:17632:5)
    at Module._compile (module.js:624:30)
    at Module._extensions..js (module.js:635:10)
    at Object.require.extensions.(anonymous function) [as .js] (/__CENSORED__/react/fixtures/ssr/node_modules/babel-register/lib/node.js:152:7)
    at Module.load (module.js:545:32)
    at tryModuleLoad (module.js:508:12)
    at Function.Module._load (module.js:500:3)
    at Module.require (module.js:568:17)
    at require (internal/module.js:11:18)
```

The exception pointed to this line:
```js
// We capture a local reference to any global, in case it gets polyfilled after
// this module is initially evaluated.
// We want to be using a consistent implementation.
const localRequestAnimationFrame = requestAnimationFrame;
```

**Test plan**

1. In `react` repo root, `yarn && yarn build`.
2. In `fixtures/ssr`, `yarn && yarn start`,
3. In browser, go to `http://localhost:3000`.
4. Observe the fixture page, not the exception message.

packages/shared/requestAnimationFrameForReact.js

@@ -15,7 +15,10 @@ import warning from 'fbjs/lib/warning';
 // We capture a local reference to any global, in case it gets polyfilled after
 // this module is initially evaluated.
 // We want to be using a consistent implementation.
-const localRequestAnimationFrame = requestAnimationFrame;
+const localRequestAnimationFrame =
+  typeof requestAnimationFrame === 'function'
+    ? requestAnimationFrame
+    : undefined;
 
 if (__DEV__) {
   if (