ScreenSharing as VNC client/viewer doesn't work in Yosemite I was using built in ScreenSharing app to connect to a VNC server running on a Linux box.

After upgrading to Yosemite the ScreenSharing icon on my Dock is a question mark now. Does OS X no longer have a built in VNC client?
On OS X Yosemite the Screen Sharing app moved to the applications subfolder:

/System/Library/CoreServices/Applications