evas: fix double free.

evas: fix double free.

The ownership of this list and its content belong to the iterator. This code
was actively double freeing and our test suite doesn't crash or have any issue...
Well actually it was complaining that the list had error, but due to our other
false positive test that do trigger eina log, we continuously ignored this error.

NOTE: The fact that the test rely also on the container of the iterator instead
of the iterator itself is not that great to. I kind of feel bad now for having
allowed access to the container. We should have been able to allow changing the
logic to generate those rectangle step after step instead of in one go. Now this
seems difficult.