Merge pull request #1136 from najor/hotfix-0.24.x-fix-indexof

Function 'indexOf' is not supported in IE9 documentMode 7.
IE: Right click on selected content does not remove the selection.

The problem was that 'beforepaste' event was thrown when right clicking. The 'beforepaste' event was used to copy/paste content for IE. With this fix the 'beforepaste' event is not necessary any more, the whole copy/paste process is done in the 'paste' event. This solution is only for IE8 and below. For other IE versions (9 and above) the event 'beforepaste' is still needed.