Chrome is no longer a web kit browser since Chrome 28.0.1500. - Reference (https://en.wikipedia.org/wiki/Google_Chrome_release_history)
It is still being set as a web kit brower in Load.php.
Also this line
'is_webkit' => strpos($_SERVER['HTTP_USER_AGENT'], 'AppleWebKit') !== false,
I believe is a bad idea, just because if a browser has AppleWebKit in the user agent string doesn't mean that it is a web kit browser.
The current version of Chrome is VER 46.0.2490, I believe it is safe to say that most versions in the wild no longer have the webkit engine.
So change the line above to.
'is_webkit' => strpos($_SERVER['HTTP_USER_AGENT'], 'AppleWebKit') !== false && strpos($_SERVER['HTTP_USER_AGENT'], 'Chrome') === false,
And this
$context['browser']['is_chrome'] = $context['browser']['is_webkit'] && strpos($_SERVER['HTTP_USER_AGENT'], 'Chrome') !== false;
To
$context['browser']['is_chrome'] = strpos($_SERVER['HTTP_USER_AGENT'], 'AppleWebKit') !== false && strpos($_SERVER['HTTP_USER_AGENT'], 'Chrome') !== false;
This will fix the positioning issues in Chrome with the WYSIWYG editor.