Consider using CSS.escape for selectors in JavaScript

[bsclifton]

Carried over from brave/browser-laptop#265

There are certain strings that are valid when used as an HTML element's id or class attributes, but not valid as a CSS selector string. They include strings that begin with numbers, contain spaces, or contain characters with special meaning in CSS. Mathias Bynens's explanation delves into the full details.

The CSS.escape() method provides a convenient way to escape a string so that it conforms to the CSS selector requirements. This is especially useful when dynamically building a CSS selector based on (untrusted) user input.

For more info, see:

• https://googlechrome.github.io/samples/css-escape/index.html
• https://developer.mozilla.org/en-US/docs/Web/API/CSS/escape