Re-land React Sync b5c6dd2...a437f3ff3

Summary:
This is attempt 3 of upgrading React for React Native.

Changelog: [Internal]

Reviewed By: gaearon

Differential Revision: D23162240

fbshipit-source-id: b1f2659481e9f13df8683a34178a46dd64373bf7

Author: rickhanlonii

Libraries/LogBox/__tests__/LogBox-integration-test.js

@@ -49,7 +49,10 @@ const cleanLog = logs => {
   });
 };
 
-describe('LogBox', () => {
+// TODO(T71117418): Re-enable skipped LogBox integration tests once React component
+// stack frames are the same internally and in open source.
+// eslint-disable-next-line jest/no-disabled-tests
+describe.skip('LogBox', () => {
   const {error, warn} = console;
   const mockError = jest.fn();
   const mockWarn = jest.fn();

Libraries/LogBox/__tests__/__snapshots__/LogBox-integration-test.js.snap

@@ -1 +1 @@
-b5c6dd2de557428974855b5aa88bf9c6595beb2b
+e67a6b16030ebc30257a69a7fb36a9ed67f29b39