Don't consider drops on a row as drops on the row's item

Since d3839617 in details view mode
clicking anywhere within the row is considered a click on the item.
That commit also changed it so that dropping files anywhere inside
a row would make it so the files are received by the folder of that
row.

This commit reverts the drop behaviour to be identical to the old
one.

I am having trouble explaining why this is better because one can
look at it in different ways. Bottom line is that one doesn't
really feel like one is dropping files inside a folder unless the
mouse cursor is actually directly above a folder's icon or name.

Another argument is that it is normal behaviour to just throw files
onto an application and the files then being opened by it.
Having potentially large parts of the view area covered by the rows
of folders means that there has to be more of a conscious effort to
not drop the files inside one of the folders by accident while with
this commit one has to aim precisely onto a folder to do it
intentionally.

CCBUG: 453700