When I do save operation with help of Ctrl-s shortcut I see the error in console Uncaught LiveEdit Failure: Failed to compile new version of script: SyntaxError: Unexpected token ? But this error line doesn't have the location so I have to scan entire text for the errors. It slows down the development process because we also don't highlight the syntax errors in the editor.
Closing as invalid, as this bug pertains to the old inspector UI and/or its tests. Please file a new bug (https://www.webkit.org/new-inspector-bug) if the bug/feature/issue is still relevant to WebKit trunk.