doc_popup.py: fix typo that was breaking positioning hack
doc_popup.py: fix typo that was breaking positioning hack

We were trying to allocate the text view in the doc popup large enough
to avoid incremental resizing, but instead of allocating it at
10000x100000 it was allocated at 10000x100.

https://bugzilla.gnome.org/show_bug.cgi?id=614312

alexey4petrov/reinteract,alexey4petrov/reinteract,alexey4petrov/reinteract