Properly treat namespace-only events for `globalUnbind()` as pertaining to both `document` and `window`.

Events with only namespaces (`.name.space`, and also the empty string)
should be treated by `globalUnbind()` as pertaining to both `document`
and `window`, so no events will be left behind.
Merge pull request #878 from odnamrataizem/gc

Properly treat namespace-only events for `globalUnbind()` as pertaining to both `document` and `window`.