By deferring allocation of StaticNodeList objects until we know somebody
actually wants the MutationRecord, we avoid a *lot* of allocation work.
This shaves several seconds off of loading https://tc39.es/ecma262/
At least one other engine (WebKit) skips creating mutation records if
nobody is interested, so even if this is observable somehow, we would
at least match the behavior of a major engine.
JS::PrimitiveString::create uses `is_empty()` on DeprecatedString to
use the empty string cache on the VM. However, this also considers the
DeprecatedString null state to be empty, giving an empty string instead
of `null` for null DeprecatedStrings.
Note that as of this commit, there aren't any such throwers, and the
call site in Heap::allocate will drop exceptions on the floor. This
commit only serves to change the declaration of the overrides, make sure
they return an empty value, and to propagate OOM errors frm their base
initialize invocations.
This needs to happen before prototype/constructor intitialization can be
made lazy. Otherwise, GC could run during the C++ constructor and try to
collect the object currently being created.
DeprecatedFlyString relies heavily on DeprecatedString's StringImpl, so
let's rename it to A) match the name of DeprecatedString, B) write a new
FlyString class that is tied to String.
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
These classes only needed Window to get at its realm. Pass a realm
directly to construct DOM and WebIDL classes.
This change importantly removes the guarantee that a Document will
always have a non-null Window object. Only Documents created by a
BrowsingContext will have a non-null Window object. Documents created by
for example, DocumentFragment, will not have a Window (soon).
This incremental commit leaves some workarounds in place to keep other
parts of the code building.
