When a URL is dropped on a Firefox window, the "text/x-moz-url" data
takes precedence over the "text/uri-list". The "text/x-moz-url" is
interpreted as UTF16, however, the data from Qt 5 applications is not
in the correct format. The code to create correct UTF16 data exists,
but it is not called for two reasons: The atomName will never be
"text/x-moz-url" because it is changed to "text/uri-list" by
mimeAtomToString() and the InternalMimeData::hasFormatHelper() case is
already handled above and the else part will never be considered.
This patch fixes the check and brings it into the right order.

Task-number: QTBUG-49947
Change-Id: I5ebd31914cc6c1417c513c1ff09e0e858a16915d
Reviewed-by: Dmitry Shachnev <mitya57@gmail.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>