Fix core code so IE8 will once again pass core tests/LoaderTest.js

- Oop.js: change code to not use function names, but instead a variable holding function ref in the closure to avoid IE8 scoping problems
- lang.js: update enyo.isObject to explicitly check for null/undefined, as those identify as "{object Object]" in IE8
- fullscreen.js: guard calls to addEventListener; they won't be made on IE8
- Add core tests for enyo.isObject and enyo.isArray
- Modifiy LoaderTest.js to do nothing on IE8, since we don't support loader there

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)