create-react-app not working with IE11 in development mode

Created by: dcp12345678

Is this a bug report?

yes

Can you also reproduce the problem with npm 4.x?

Unknown

(Write your answer here.)

Which terms did you search for in User Guide?

(Write your answer here if relevant.)

Environment

1. node -v: v6.11.2

2. npm -v: 3.10.10

3. yarn --version (if you use Yarn): N/A

4. npm ls react-scripts (if you haven’t ejected): react-scripts@1.0.12

Then, specify:

1. Operating system: Windows 7
2. Browser and version (if relevant): IE 11

Steps to Reproduce

(Write your steps here:) I am on Windows 7, so these instructions reflect that environment.

1. create-react-app my-app
2. cd my-app
3. npm start
4. In IE11, navigate to http://localhost:3000
5. Press F12
6. Press F5
7. You will see an error about Object.assign not being defined.

Expected Behavior

(Write what you thought would happen.)

I expect not to get an error.

Actual Behavior

Got the error about Object.assign

(Write what happened. Please add screenshots!)

Reproducible Demo

(Paste the link to an example project and exact instructions to reproduce the issue.)