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`.
Any case where `node.get('tag') == 'style'` would not have `node.styleSheet`?