The JavaScript Console in the Web Inspector has some kind of auto completion going on, but the standard OS X mechanism of popping up a list of potential completions by pressing F5 or Option-Esc doesn't work. Esc opens and closes the console, Option-Esc does nothing, and F5 completes words from the system dictionary. It would be great to have a completion list for those times when you can't quite remember the name of a function.
You can press the tab key to cycle through multiple matches.
*** This bug has been marked as a duplicate of bug 65511 ***