What's new in the WebKitGTK 2.53.90 release?
============================================

  - Do not support rendering tiles in the main thread in accelerated compositing mode.
  - Add magnification property to WebKitWebView to handle visual scaling.
  - Add new API to allow setting a per-navigation custom User-Agent to WebKitWebsitePolicies.
  - Improved platform media queries to handle prefers reduced motion, high contrast and dark theme.
  - Fix several crashes and rendering issues.
  - Translation updates: Brazilian Portuguese, Slovenian.