Comparison with QtWebKit 5.6

Feature	5.8	Alpha
ES2015	✘	✔
Responsive images	✘	✔
HTML <template>	✘	✔
CSS selectors ::read-write and ::read-only	✘	✔
CSS property -webkit-initial-letter	✘	✔
Fullscreen API	✘	✔
WebAudio	✘	✔ (Experimental with GStreamer)
MediaSource	✘	✔ (Experimental with GStreamer)
Encrypted Media	✘	✘ (Planned for GStreamer, help needed)
APNG images	✘	✔
B3 JIT compiler	✘	✔ (Not available on Windows yet)
CSS selector JIT	✘	✔
Indexed Database	✔	✔
Indexed Database in Workers	✔	✘ (supported in WebKit trunk)
Private browsing	✔	✔
Smooth scrolling	✔	✔
Tiled backing store	✔	✘ (Will come back someday)
WebGL	✔	✔
Web SQL Database	✔	✔
Accelerated compositing	✔	✔
NPAPI Plugins	✔	✔ (Not available on macOS yet)
Qt Plugins	✔	✔
QML API	✔	✔ (not available on Windows, see wk2 branch
QML API: Downloads	✔	✔
QML API: Authentication	✔	✘ (Planned)
QML API: Custom URL Schemes	✔	✘ (Planned)
QML API: WebGL	✔	✘ (Planned)
QML API: NPAPI plugins	✔ (Only X11)	✘ (WIP, only X11)
QML API: Fullscreen	✔	✘ (Planned)
Security fixes	✘	✔

Important behavior changes

• Mixed content is blocked by default. To restore old behavior set QWebSettings::AllowRunningInsecureContent attribute to true
• Now application code must handle QWebPage::fullScreenRequested signal to get fullscreen working. It's necessary because latests HTML standard specifies that any web element can go fullscreen, not only video
• JPEG and PNG images no longer use Qt plugins (qpng and qjpeg) on Windows and macOS (actually, on any OS if Qt build uses bundled libraries)