Revert Text to 0.7-version (Fixes #137)

If onAttach/onDetach are not overridden then those are called from widget where
DOM.setEventListener(getElement(), this);
is called.
This method is apparently not available for text nodes in IE8.
Merge pull request #204 from LeovR/patch-1

Revert Text to 0.7-version (Fixes #137)