Significantly slower under Meteor and unbundled server contexts

[jimrandomh]

Apollo-Client is significantly slower when running out of a Meteor server environment or a node_modules folder than when it's running inside of a bundle which has had process.env.NODE_ENV preprocessed into a string. This PR fixes it, but seems to have fallen through the cracks. The problem is that in node, process.env is actually a slow API function, not suitable for being called in any sort of inner loop, but apollo-client is using it as though it was fast.

[benjamn]

@jimrandomh You're right about process.env.NODE_ENV being slow in Node, but (unfortunately!) the syntax of the process.env.NODE_ENV === ... checks is important for minifiers to be able to strip out development-only code in production. I don't love that convention, but it's the same convention React uses, so various bundlers and starter codes will already have it configured, which saves Apollo Client from introducing its own additional requirements for proper minification. In Meteor, although the JS minifier does automatically replace process.env.NODE_ENV with a string literal, minification happens only for browser code, which is why process.env.NODE_ENV remains intact.

[hwillson]

Let us know if this is still a concern with @apollo/client@latest - thanks!