Adding or adjusting front-end function and variable documentation per our conventions.

Adding or adjusting front-end function and variable documentation per our conventions.

Also did some trivial clean up, JSHint fixes and performance optimizations while at it. (per http://www.mediawiki.org/wiki/JavaScript_performance )
* Missing semicolons.
* [mediawiki.js Line 540] Unreachable 'registry' after 'throw'.
* [mediawiki.log.js] Checked for window.console but used console.
* Added callback option to mw.util.toggleToc (forwarded to jQuery.fn.slideUp/Down)
* Made mw.log argument more descriptive (logmsg instead of string)
* Using deepEqual(, true) instead of ok() when asserting true. (ok() is like casting a boolean (or a plain if() statement) to verify that something is not falsy)

Added missing test suites for:
* mw.util.toggleToc (follow-up r88732, Dummy check was introduced in r87898)

/me has been infected by Reedy and will be doing more of this tonight.