Buffer 4.9.2 refers to `global` which is a node-only feature.

It seems that Buffer 4.9.2, which is explicitly a browser polyfill, tries to access a `global` variable, which as far as I can tell, is only available on Node. Why I haven't run into this before today I can't tell, but suddenly an Angular project I'm working on starting having trouble with this. It goes through the `amazon-cognito-identity-js` dependancy, which even in the latest version explicitly requires 4.9.2. I don't know why this suddenly happened, and I guess with 13 million downloads it probably isn't a bug, but I don't really know what's going on.