updated 10:00 pm EDT, Tue March 18, 2014
Developer-only betas focus on site compatibility, push notifications, more
Following its release earlier today of a 10.9.3 Mavericks preview and iTunes 11.1.6 beta, Apple has added new Safari betas for developers to test. The pre-release builds, versions 6.1.3 and 7.0.3 (Lion/Mountain Lion and Mavericks, respectively), are expected to accompany the release of OS X Mavericks 10.9.3 when it emerges from beta.
In the release notes, Apple asks developers to focus testing on general website compatibility, Safari Push Notifications, login autofill and extension compatibility. For the Mavericks version, developers are also asked to test credit card autofill, a feature found in the iCloud Keychain.
Apple has been winding down support for the four-year-old OS X 10.6 Snow Leopard, and is not expected to continue providing updates for that OS version with the exception of security and potentially some iTunes/QuickTime updates. It began omitting Snow Leopard from Safari updates last September with version 5.1.10.