Per the spec, the observer's [[scrollMargin]] should be applied to
each scroll container's scrollport when walking the containing block
chain. This expands the effective clip rect, allowing targets to be
detected as intersecting before they actually enter the visible area
of the scroll container.
Add a scroll_margin_values() accessor to IntersectionObserver so the
raw LengthPercentage values can be used during intersection computation.
The scroll margin is applied by inflating the scroll container's
padding box rect before clipping the intersection rect against it.
Remove unused/redundant includes from Element.h:
- AK/IterationDecision.h (redundant)
- ARIA/AttributeNames.h (redundant via ARIAMixin.h)
- CSS/CascadedProperties.h (redundant via PseudoElement.h)
- CSS/StylePropertyMapReadOnly.h (pointer types only)
- HTML/LazyLoadingElement.h (unused in header)
Extract IntersectionObserverRegistration struct from
IntersectionObserver.h into its own lightweight header.
This breaks the heavy transitive include chain through
IntersectionObserverEntry.h and Geometry/DOMRect.h that
was pulled into every file including Element.h.
Indirect recompilation impact reductions:
- IntersectionObserver.h: ~1387 -> ~27 files
- LazyLoadingElement.h: ~1387 -> ~1002 files
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
