[Grid] IE 11 support

If you include the Grid component, an error occurs in URL search of Google search console. This problem does not occur at least on Chrome and Edge. As there is no complaint from the user, it will not occur in Safari, too.

Problems began to occur in May. Until then, screenshots were displayed in the Google Search Console. I think that the change of Google Crawler is affecting. Even my code needed to be corrected in two places.

As I am not good at English, I write with the help of translation.

• This is not a v0.x issue.
• [x ] I have searched the issues of this repository and believe that this is not a duplicate.

Expected Behavior 🤔

A screen shot will be displayed.

Current Behavior 😯

Screen shots are not displayed. Console error message: TypeError: undefined is not a function

Steps to Reproduce 🕹

Link:

1. Create a component that contains a Grid component. (ex. return (<Grid></Grid>);)
2. npm run build
3. Deploy in an environment accessible by Google Search Console.
4. Run a live test of URL inspection from Google Search Console.

Context 🔦

I’m expecting the crawler to understand the page correctly.

Your Environment 🌎

Tech	Version
Material-UI	v4.0.0
React	v16.8.6
Browser	Google Search Console
TypeScript
react-router-dom	v5.0.0
react-scripts	v3.0.1

[qrusadorz]

I confirmed that it was improved in v 4.0.2. I used Google’s Mobile-Friendly Test Site. Thank you very much.

[oliviertassinari]

@qrusadorz Thank you for trying it out. The problem is in this line: https://github.com/mui-org/material-ui/blob/8cfaa9880ad59b8c11121ce507dacad54aba13ce/packages/material-ui/src/Grid/Grid.js#L61

It was transpiled in beta.1 but it’s not longer in beta.2 (and in v4.0.1).

I think that we should add Object.assign back as it’s not supported by IE 11 or rewrite the source to move away from Object.assign. No matter what, we have an issue with the end-to-end tests. The problem wasn’t detected. What do you think @eps1lon?