Why do you use WebKit?
Where are many problems with WebKit that likely won't be fixed soon because they are already fixed on Safari's (e.g #1554 (closed), #1551 (closed)) side or because Linux and GNOME is not important for WebKit's developers (e.g. #1453 (closed), #1185 (closed)) or even because it's unsolved WebKit's problems. WebKit doesn't support a lot of features that Blink and Quantum support.
Why don't you use Firefox's Quantum or Chromium's Blink?