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`.
Actually this is odd. Why iterate through all the properties. 

This would only be applicable to text.

``` js
propertySetters.text = (function(setter){
  return function(node, value){
    if (node.get('tag') == 'style') node.set('html', value);
    else  node.value = value;
  };
})(propertySetters.html);
```