Log Message:
webkit-gtk: Update to 2.26.0

pkgsrc changes:
 - When built with gcc, 7.3.0 or newer is now needed

Changes:
WebKitGTK 2.26.0
================
 - Disable process swap on navigation.
 - Do not enable the sandbox in Snap.
 - Fix sandbox parsing DISPLAY on X11.
 - Translation updates: Brazilian Portuguese, German.

WebKitGTK 2.25.92
=================
 - Add WEBKIT_USE_SINGLE_WEB_PROCESS environment variable to force single
   process model in all WebKitWebContext.
   This is a temporary solution for applications still depending on the
   single process mode behavior. It will be only available in 2.26 series.
 - Add new API to remove a filter from an user content manager given its
   identifier.
 - Add support for HSTS.
 - Several improvements and bug fixes in MSE media player.
 - Fix building without unified sources.
 - Fix several crashes and rendering issues.
 - Translation updates: Polish, Ukrainian.

WebKitGTK 2.25.4
================
 - Switch to use libsoup WebSockets API.
 - Add support for permessage-deflate WebSocket extension.
 - Add support for datalist element in text input fields.
 - Fix a crash with empty video source.
 - Fix several crashes and rendering issues.

WebKitGTK 2.25.3
================
 - Remove support for GTK2 NPAPI plugins.
 - Fix web view updates after swapping web process if accelerated
   compositing mode is forced.
 - Make kinetic scrolling work again.
 - Fix position of emoji chooser when page is scrolled.
 - Fix web process deadlock when scrolling twitter timeline which contains
   HLS videos.
 - Make navigation gesture use dark fallback background color color on dark
   themes.
 - Make Previous/Next gesture work in RTL mode.
 - Support cancelling touchscreen back/forward gesture.
 - Add user agent quirk to make github work in FreeBSD.
 - Fix content disappearing when using CSS transforms.
 - Fix some radio streams that could not be played.
 - Fix video pause that sometimes caused to skip to finish.
 - Fix volume level changes when playing a video.
 - Fix several crashes and rendering issues.

WebKitGTK 2.25.2
================
 - Enable process switch on cross site navigation.
 - Use libwpe with fdo backend to implement accelerated compositing under
   wayland.
 - Fix rendering artifacts in youtube volume button.
 - Fix trapezoid artifact in github comment box.
 - Ensure web extensions directory is readable when sandbox is enabled.
 - Fix the executable name of WebDriver process, renamed by mistake in
   2.25.1.
 - Enable hyperlink auditing setting by default.
 - Remove the option to build without using the redirected XComposite window.
 - Fix HLS streams being slow to start.
 - Make accessibility work when sandbox is enabled.
 - Fix several crashes and rendering issues.

WebKitGTK 2.25.1
================
 - Add support for subprocess sandboxing.
 - Add API to get the web process unique identifier of a WebKitFrame.
 - Add WebKitWebPage::did-associate-form-controls-for-frame signal and
   deprecate did-associate-form-controls.
 - Implement AtkComponentIface scroll_to methods.
 - Improve rendering of form controls when GTK theme is dark and enable
   prefers-color-scheme media query.
 - Show the emoji chooser popover for editable content.
 - Fix touch capabilities detection for websites checking touch events
   properties present in window or pointer media queries.
 - Fix several crashes and rendering issues.