Don't perform focus node native selection trick while dragging

1) The trick is so FF fires a copy event when there is no
text selected. In the case of dragging there will be something selected.
2) It breaks the native selection so you can't continue dragging.

Bug: 71139
Change-Id: I2663968b693c8992b942ab6d5b429d7552c34a5d
Merge "Don't perform focus node native selection trick while dragging"