This morning I was prompted by Webkit to install a new update. I forget what the build number was on the dialog. I accepted. After that when I launched Webkit a message was displayed: "Unable to launch Safari Webkit is located at a path containing an unsupported character. Please move Webkit to a different location and try again." I checked, but webkit was still in my "Applications" folder. I downloaded the dmg file manually from the webkit site using Firefox and replaced my current app. Now it works again. Not sure if the next auto update will break it again.
Created attachment 27011 [details] For bug 23527
That error will be displayed if the path where your copy of WebKit lives contains a ":" character. The ":" character is used as a delimiter so cannot appear in the path to the WebKit application. This is not new behaviour, it has been present in the nightly builds since day zero.
Created attachment 27017 [details] this is what happens to the webkit icon after the error
I don't know what you've done, but that's clearly not the WebKit icon. I suspect you've somehow copied another application over WebKit in some manner.