This is a monster patch that turns all EventTargets into GC-allocated
PlatformObjects. Their C++ wrapper classes are removed, and the LibJS
garbage collector is now responsible for their lifetimes.
There's a fair amount of hacks and band-aids in this patch, and we'll
have a lot of cleanup to do after this.
This patch moves the following things to being GC-allocated:
- Bindings::CallbackType
- HTML::EventHandler
- DOM::IDLEventListener
- DOM::DOMEventListener
- DOM::NodeFilter
Note that we only use PlatformObject for things that might be exposed
to web content. Anything that is only used internally inherits directly
from JS::Cell instead, making them a bit more lightweight.
Removing the FIXME'd code in b99cc7d was a bit too eager, and relying on
the main thread VM's current realm only works when JS is being executed.
Restore a simplified version of the old code to determine the realm this
time instead of the global object, following the assumptions already
made in get_current_value_of_event_handler() regarding what kind of
event target 'this' can be.
Similar to create() in LibJS, wrap() et al. are on a low enough level to
warrant passing a Realm directly instead of relying on the current realm
from the VM, as a wrapper may need to be allocated while no JS is being
executed.
This is a continuation of the previous three commits.
Now that create() receives the allocating realm, we can simply forward
that to allocate(), which accounts for the majority of these changes.
Additionally, we can get rid of the realm_from_global_object() in one
place, with one more remaining in VM::throw_completion().
This is a continuation of the previous two commits.
As allocating a JS cell already primarily involves a realm instead of a
global object, and we'll need to pass one to the allocate() function
itself eventually (it's bridged via the global object right now), the
create() functions need to receive a realm as well.
The plan is for this to be the highest-level function that actually
receives a realm and passes it around, AOs on an even higher level will
use the "current realm" concept via VM::current_realm() as that's what
the spec assumes; passing around realms (or global objects, for that
matter) on higher AO levels is pointless and unlike for allocating
individual objects, which may happen outside of regular JS execution, we
don't need control over the specific realm that is being used there.
This patch implements the "create a new browsing context" function from
the HTML spec and replaces our existing logic with it.
The big difference is that browsing contexts now initially navigate to
"about:blank" instead of starting out in a strange "empty" state.
This makes it possible for websites to create a new iframe and start
scripting inside it right away, without having to load an URL into it.
The way we've been creating DOM::Document has been pretty far from what
the spec tells us to do, and this is a first big step towards getting us
closer to spec.
The new Document::create_and_initialize() is called by FrameLoader after
loading a "text/html" resource.
We create the JS Realm and the Window object when creating the Document
(previously, we'd do it on first access to Document::interpreter().)
The realm execution context is owned by the Environment Settings Object.
This state is less static than we originally assumed, and there are
special formatting context-specific rules that say certain sizes are
definite in special circumstances.
To be able to support this, we move the has-definite-size flags from
the layout node to the UsedValues struct instead.
Absolutely positioned boxes are handled by the BFC destructor, so we
need to make sure the ICB BFC is destroyed if we want these boxes
to get laid out.
Step 19 of node removal was missing, which allows the mutations of the
descendants of the removed node to still be observed by the parent.
Step 20 of node removal queued the mutation record for the removed
node instead of it's parent. Since queuing takes place after the node
is removed from the tree, the mutation record would be lost as the only
inclusive ancestor of the node at this point is only the node itself.
