Redundant imports from history bloating bundle sizes

[DullReferenceException]

Version

react-router-dom@4.2.2

Steps to reproduce

Create a webpack bundle that import react-router-dom

Expected Behavior

Only the main or es folder of the history library is bundled

Actual Behavior

Both the main and es folder of the history library is bundled

Theory

I believe that the issue stems from the fact that there are two different ways that things are being imported from history:

• Deep imports like require('history/createBrowserHistory')
• Direct imports like require('history')

The former type of import is bringing in JS modules in the root of node_modules/history, but the latter type is causing node_modules/es/index.js and its dependencies to be brought in due to the "main" entry point in its package.json.

In theory changing the imports to be consistent will avoid bundling all the files in both node_modules/history and node_modules/history/es.

[pshrmn]

This is a duplicate of #5576, which was fixed with #5589 but is not yet released.