Add workaround function to properly read the offsetHeight of a DOM
element. IE7 (and newer versions of IE in IE7 mode) sometimes would return
0 for the offsetHeight and only upon reading the value again would reveal
the correct value.
Merge pull request #1267 from alohaeditor/hotfix-0.24.x-rt58526

Add workaround function to properly read the offsetHeight of a DOM