Fix setter so IE7/8 can set text of style element

fixes #2265

Our setters brake old IE when setting text of a style element.
This pull request adds a alternative `propertySetters.text` in case the problem exists in the Browser.

Used some ideas from @arian's  fix on his `fix-2265-text branch`.
What's the difference between setting the `'text'` and setting the '`html'` if they're both the same (ultimate outcome) couldn't we just piggy back on the prefix fix for `styleEl.set('html')`