js-xdr cannot works well in a pre-ES2016 environment.

[overcat]

Describe the bug
The new version of js-xdr uses Buffer.subarray, but currently it does not work properly in pre-ES2016 environments. This has caused the new version of stellar-sdk to be unable to be used in React Native, because React Native uses the default JS engine that supports ES6.

I suggest reading this thread to learn more information: feross/buffer#329 (comment)

What version are you on?
3.1.0

To Reproduce
Steps to reproduce the behavior:
Run the following code in the ES6 engine, for example, Hermes, it is the default engine for React Native projects.

console.log(new XDR.Hyper(0).toXDR("base64"))

Actual output

0,0,0,0,0,0,0,0

Expected output

AAAAAAAAAAA=

Expected behavior
Works well in a pre-ES2016 environment.
Additional context
N/A

[overcat]

Hi @piyalbasu, I created a repo to reproduce this bug. You can run it if you need to.

repo: https://github.com/overcat/StellarSdkDebugApp
setup env: https://reactnative.dev/docs/environment-setup