Fix reselection of the eventTrap in IE11 & Firefox

Changing to an input element (1038583) affected how text ranges are
created in IE and Firefox. This stopped cut/paste from functioning.

setSelectionRange is supported on all major browsers.
Don't rely on boolean value being returned from DataTransfer.setData

According to the current specifications, this is a void return type.
Chrome is the only browser that returns a boolean value for this.

See http://www.whatwg.org/specs/web-apps/current-work/multipage/dnd.html#dom-datatransfer-setdata
Fix cut & copy in Internet Explorer

IE11 throws an exception when attempting to set an unsupported key such
as "text/plain". Could have done browser sniffing to detect IE instead,
but this approach seems equally valid.