The behavior here is a bit weird because Document is still not a
WebIDL object, so calling createNodeIterator or createTreeWalker via
an Xray will call the XPCOM versions of those methods. That means
that I can't just disable XPCOM-based wrapping for TreeWalker and
NodeIterator altogether, unfortunately, which means a web page could
try stashing a TreeWalker in something like userdata and then getting
it back and end up wrapping it as an XPCOM object the second time.
I could "fix" that by adding a wrapper cache and whatnot, I guess, if
desired... But the problem will go away once we convert Document in
any case.
The behavior here is a bit weird because Document is still not a
WebIDL object, so calling createNodeIterator or createTreeWalker via
an Xray will call the XPCOM versions of those methods. That means
that I can't just disable XPCOM-based wrapping for TreeWalker and
NodeIterator altogether, unfortunately, which means a web page could
try stashing a TreeWalker in something like userdata and then getting
it back and end up wrapping it as an XPCOM object the second time.
I could "fix" that by adding a wrapper cache and whatnot, I guess, if
desired... But the problem will go away once we convert Document in
any case.
There were merges in configure.in and some Makefile.in. None had any
conflicts. I spot verified the Makefile.in changes and confirmed that
the changes did not touch any DIRS* variables.
It's annoying to add yet another RAII class, but we're solving a different
problem here. In particular, there are lots of callers that grab a cx off
of an nsIScriptContext and use it without pushing. Most of the time this
is ok, since that cx is also the active cx. But it's hard to tell when we
might potentially violate that invariant. What's more, we don't want to just
use an nsCxPusher, because that does expensive things even when the cx matches
the one on the top of the stack. Most of these consumers should just switch
to AutoJSContext, but doing such a change en masse is a pretty risky thing to
do. So let's introduce a class that gives us good performance in the common case
and correctness in the uncommon case.
We leave the nsIDOMEventTarget* versions fallible for now, but this makes the
common case a lot simpler. Note that this means that pushing a null JSContext,
a bug, is no longer handled at runtime. But I think we should just assert
against it, since there are already callers that don't check the return value.
The goal here is to get rid of this crap entirely, and make nsCxPusher always
push. But that's a scary change, so we do it in chunks. This patch, in particular,
should have zero behavioral change. This means preserving some very wrong behavior.
For instance, currently SafeAutoJSContext never pushes a damn thing, because the
safe JSContext doesn't have an associated nsIScriptContext. We preserve this
behavior, and in fact convert various similarly-buggy consumers to
SafeAutoJSContext, so that we can hoist the behavioral change into a subsequent
patch.
We leave the nsIDOMEventTarget* versions fallible for now, but this makes the
common case a lot simpler. Note that this means that pushing a null JSContext,
a bug, is no longer handled at runtime. But I think we should just assert
against it, since there are already callers that don't check the return value.
