Here's the full overview of what's new:
NEW: Support for Retina Display on OS X 10.7 and up NEW: Preliminary support for WebRTC CHANGED: Experience better image quality with our new HTML scaling algorithm CHANGED: Performance improvements around tab switching DEVELOPER: CSS3 Flexbox implemented DEVELOPER: Support for new DOM property window.devicePixelRatio DEVELOPER: Support for @supports added DEVELOPER: Improvement in startup time through smart handling of signed extension certificates HTML5: Support for W3C touch events impemented, taking the place of MozTouch events FIXED: Disable insecure content loading on HTTPS pages (62178) FIXED: Improved responsiveness for users on proxies (769764)