SideBySide2: Clear selection when making new range comment

Immediately clear the selection when inserting the new draft widget.
Focus will move into the widget and the selected text will now be the
bright yellow color used when showing the text the comment applies to.
This is now consistent with how the UI will look if the user saves the
draft, does other stuff, and then comes back and edits this draft.

Change-Id: Ia3f03aef80d777b9c9a9d96ad944972fe3f65168
2 files changed