P5.js-web-editor: Update CSSLint to StyleLint

[hellonearthis]

I was trying to use css grids fr units and they didn't seem to work, gave me a red squiggly

• Found a bug
  I don't know if it's a bug or something that's not supported or if I've made a booboo

Details about the bug:

The css I used was
`html, body {
height: 100%;
margin: 0px;
padding: 0;

display: grid;
grid-template-columns: 1fr 1fr ;
grid-gap: 10px;
background-color: #f2f2f2;
`

• Web browser and version: Version 80.0.3987.163 (Official Build) (64-bit)

• Operating System: Windows 10 Pro

• Steps to reproduce this bug:
  That css code above.

[catarak]

Thanks for reporting! My hunch is that csslint, the package that is doing the static analysis to check for errors in the CSS, needs to be updated. Going to try it out now!

[catarak]

So apparently this is an open issue with CSSLint :(, see CSSLint/csslint#734.

[catarak]

The JSFiddle maintainers found a solution but it's not clear what exactly the solution was, see https://github.com/jsfiddle/jsfiddle-issues/issues/1377.

[catarak]

It seems like the way to fix this is to move from CSSLint to StyleLint, see https://discuss.codemirror.net/t/promises-support-for-the-linter-add-on/1140/4 for reference on how to make StyleLint work with CodeMirror.