Link Random text.

This test checks selection drag edge cases on Mac. To run the test manually:

1. Select everything above, start the drag over the image, and with no delay, drag it to the content editable area. Only the image should be dragged.
2. Select everything above, start the drag over the link, and with no delay, drag it to the content editable area. The entire selection should be dragged.
3. Select everything above, start the drag over the text, and with no delay, drag it to the content editable area. Nothing should be dragged, but a bunch of text should be selected instead.