[IMP] web: extra comments to explain commit 57b4860

Added some cryptic comments so we remember a bit
why we have a complicated dance with on_close.
Basically we do not want to reload the
original form view until the last popup is closed,
in the case where several wizard (steps) are opened
one after the other.
Merge branch '7.0' of https://github.com/odoo/odoo into 7.0-linux64