

Apple also documents several new WebKit features included in the new versions of Safari including support for WebGL, which allows users to view 3D content without plug-ins. WebGL has been present in Safari for OS X for several years, but is disabled by default. It's clear, however, that Apple is looking to take WebGL mainstream, pushing development on OS X Safari and bringing it to Safari for iOS later this year with iOS 8.Please test general website compatibility.
- Subpixel rendering is now on by default for all web content. Web sites or in-app web views with extremely tight design constraints may render differently.
- CSS object model getters will return fractional double values based on subpixel layout and rendering metrics instead of rounded integral values.
Please test extension compatibility.
Update: Many non-developers are reporting that the Safari 7.1 beta is even showing up for them in the Mac App Store update section.
Article Link: Apple Seeds New Versions of Safari for Mavericks and Mountain Lion to Developers