Summary:
This PR is a followup to https://github.com/facebook/react-native/pull/11417 and should be merged after that one is merged.
1. Add support for creating blobs from strings, not just other blobs
1. Add the `File` constructor which is a superset of `Blob`
1. Add the `FileReader` API which can be used to read blobs as strings or data url (base64)
1. Add support for uploading and downloading blobs via `XMLHttpRequest` and `fetch`
1. Add ability to download local files on Android so you can do `fetch(uri).then(res => res.blob())` to get a blob for a local file (iOS already supported this)
1. Clone the repo https://github.com/expo/react-native-blob-test
1. Change the `package.json` and update `react-native` dependency to point to this branch, then run `npm install`
1. Run the `server.js` file with `node server.js`
1. Open the `index.common.js` file and replace `localhost` with your computer's IP address
1. Start the packager with `yarn start` and run the app on your device
If everything went well, all tests should pass, and you should see a screen like this:
![screen shot 2017-06-08 at 7 53 08 pm](https://user-images.githubusercontent.com/1174278/26936407-435bbce2-4c8c-11e7-9ae3-eb104e46961e.png)!
Pull to rerun all tests or tap on specific test to re-run it
[GENERAL] [FEATURE] [Blob] - Implement blob support for XMLHttpRequest
Closes https://github.com/facebook/react-native/pull/11573
Reviewed By: shergin
Differential Revision: D6082054
Pulled By: hramos
fbshipit-source-id: cc9c174fdefdfaf6e5d9fd7b300120a01a50e8c1