Avoid meta programming to initialize functions in module scope

[sebmarkbage]

I'm trying to get rid of all meta programming in the module scope so that closure can do a better job figuring out cyclic dependencies and ability to reorder.

This is converting a lot of the patterns that assign functions conditionally to using function declarations instead.

let fn;
if (__DEV__) {
  fn = function() {
    ...
  };
}

->

function fn() {
  if (__DEV__) {
    ...
  }
}

[react-sizebot]

Comparing: 21aee59...62f7e81

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	=	157.62 kB	157.62 kB	+0.02%	49.84 kB	49.85 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	159.67 kB	159.67 kB	=	50.54 kB	50.52 kB
facebook-www/ReactDOM-prod.classic.js	=	542.26 kB	542.23 kB	=	96.24 kB	96.23 kB
facebook-www/ReactDOM-prod.modern.js	=	526.12 kB	526.09 kB	=	93.94 kB	93.94 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 62f7e81

[acdlite]

[acdlite]

jk I read it to check if it would conflict with the PR I'm working on