Subject of the issue

Remark appears to be mishandling text inside square braces, possibly attempting to create a link reference, even though the text in braces is over two lines.

This is hard to describe. I think the reduction below will explain it better.

Your environment

• OS: MacOSX and also reproduced on REPL.it - https://repl.it/repls/RegalHandmadeWifi
• Packages: Latest Remark and Remark-HTML
• Env: Node v12

Steps to reproduce

Run this reduction:

const remark = require('remark');
const html = require('remark-html');

const md = new remark().use(html);

const markdown = `
[one]
[two]
[three]
[four]
[five]
`;

md.process(markdown, (error, result) => {
  if (!error) {
    console.log(String(result));
  }
});

Expected behaviour

Same as what happens on Commonmark Dingus:

https://spec.commonmark.org/dingus/?text=%5Bone%5D%0A%5Btwo%5D%0A%5Bthree%5D%0A%5Bfour%5D%0A%5Bfive%5D

<p>[one]
[two]
[three]
[four]
[five]</p>

Actual behaviour

Only every second newline is retained:

<p>[one][two]
[three][four]
[five]</p>

Inside a paragraph this is not a huge deal (although white space is lost there), but inside pre or textarea tags (where this also occurs) this is not desirable.