More mediawiki.js cleanup

More mediawiki.js cleanup
- Convert prototype object modifications into object literal. Saves bandwidth (less characters) and speeds up execution (no need to access 2 level deep object member repetitively). Local testing (Chrome Web Inspector) shows 14.80KB to 14.67KB (non-cached, debug=false), and execution time on cached request 32ms to 25ms.
- Un-indent 1 tab for d.setTime (Follows up r92964)
- Whitespace consistency
- Move var statements to top of loader's addScript

Follows up: r92933