Before this change, `m_needs_repaint` was reset in
`Document::record_display_list()` only when the cached display list was
absent. This meant that if the last triggered repaint used the cached
display list, we would keep repainting indefinitely until the display
list was invalidated (We schedule a task that checks if repainting is
required 60/s).
This change also moves `m_needs_repaint` from Document to
TraversableNavigable as we only ever need to repaint a document that
belongs to traversable.
The use of this HashMap looks very spooky, but let's at least use
finalize when cleaning them up on destruction to make things slightly
less dangerous looking.
Corresponds to https://github.com/whatwg/html/pull/10683
As part of this, I noticed we incorrectly were setting the "is popup"
flag on the Navigable instead of the BrowsingContext. I've fixed that
and removed the erroneous flag from Navigable.
To check whether a NavigationParams is null, we have to check whether
it's `Empty` or `NullWithError`. Instead, we can merge both of these
possible variants into an optional error. If `NullOrError` has no
value it's null, otherwise it contains an error message.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
