Safari 8.0.3 for OS X Yosemite is included in beta builds of OS X 10.10.2
Safari 7.1.3 for OS X Mavericks requires OS X 10.9.5
Safari 6.2.3 for OS X Mountain Lion requires OS X 10.8.5
The company has outlined several focus areas for testing.
• General website compatibility
• Extension compatibility
• Password AutoFill
• HTML5 video playback on popular video sites
• Using the Web Inspector to debug websites
• Reading List read/unread state
• Editing bookmarks in the Favorites Bar and Bookmarks Sidebar
• Website notifications
Developers can download the betas from the link below...