Summary:
`polyfillLazyGlobal` used a top level this which get stripped by babel `transform-es2015-modules-commonjs` with the default config. This is mainly an issues for people not using the react native babel preset.
This also replaces a few GLOBAL with global for consistency with the rest of the file.
**Test plan**
Tested that there was an error when using `['transform-es2015-modules-commonjs', { strict: true, allowTopLevelThis: false }]` in the babel config and that it was fixed after applying my changes.
Fixes#7700
Closes https://github.com/facebook/react-native/pull/7971
Differential Revision: D3427675
Pulled By: javache
fbshipit-source-id: 48f258b0db1bf21185193bd56df453ced9242e64
f9e26b327b