Introduce a new SpinningSynchronousClose API that allows to synchronously close
a connection that executed asynchronous statements, by spinning the events loop.
This is expected to be used rarely in particular cases like database corruption.
It is currently [noscript] since the only consumer is cpp, in the future we can
evaluate removing that, if we find more uses for it.
MozReview-Commit-ID: 7SPqutoF9jJ
The new name makes the sense of the condition much clearer. E.g. compare:
NS_WARN_IF_FALSE(!rv.Failed());
with:
NS_WARNING_ASSERTION(!rv.Failed());
The new name also makes it clearer that it only has effect in debug builds,
because that's standard for assertions.
