A notepad will persist your code and allow you to edit it easily, including newlines and tabs. It will also allow you to undo/redo. Try FireBug to see what I mean.

Yes, in Chrome you can technically hit "Shift+Enter" anytime you want a line break, but you cannot tab. Regardless your script will disappear after you execute it. Yes, you can make what you just typed reappear by hitting the up arrow, but then it's again difficult to edit it. It also does not support undo/redo.

Why confused? Shift-Enter is a horrible way to work with multiline edits, so I wouldn't call Chrome's offering a "multiline editor" at all.

Just give us a proper multiline editor with syntax highlighting, line numbers and all the rest already.