Aborting the addition of "New element node" in XML Editor adds a node (rev >= 11065)

[FirasH]

- Steps to reproduce:

0) Create a new document
1) Go to: Edit > XML Editor...
2) Select any of the present nodes
3) Click on "New element node"
4) Click on "Cancel" or X to close the dialog

The node is added.

- Inkscape version:
0.91pre2 r13580

[su_v (suv-lp)]

Reproduced with Inkscape 0.91pre2 r13580 on OS X 10.7.5

Based on tests with archived builds:
- not reproduced with rev <= 11059
- reproduced with rev >= 11066;
this unexpected result seems to have been introduced in
  Revision 11065: Fix for bug #940715 : Convert XML Editor to a dockable dialog
  <http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/revision/11065>

Empty node element as stored in the SVG source:
    < />