Remove the CSS property -webkit-highlight intended to highlight text, but never standardized. It has no visible effect in chromium (it is parsed but never used in rendering content). The property was removed from WebKit in 2014 (https://bugs.webkit.org/show_bug.cgi?id=128456), has been marked as deprecated on MDN, and has been replaced recently with the CSS Highlight Pseudo spec (https://www.w3.org/TR/css-pseudo-4/#highlight-pseudos).
The motivation is to avoid confusion with the new CSS Highlight Pseudo and to clean up the code (removing 1K or so of memory usage).