Our previous implementation kept track of an AnimationTimeline being
monotonically increasing, by looking at new time values coming in and
setting `m_monotonically_increasing` to `false` whenever a new value
is before the previous known time value.
As far as I can tell, the spec doesn't really ask us to do so: it just
defines 'monotonically increasing' as a property of a timeline, i.e. it
guarantees that returned time values from `::current_time()` are always
greater than or equal to the last returned value.
This fixes a common crash seen when the last render opportunity lies
before the document's origin time, and `::set_current_time()` was
invoked with a negative value. This was especially visible in the
`Text/input/wpt-import/css/cssom/CSSStyleSheet-constructable.html` test.
Before this change, we were going through the chain of base classes for
each IDL interface object and having them set the prototype to their
prototype.
Instead of doing that, reorder things so that we set the right prototype
immediately in Foo::initialize(), and then don't bother in all the base
class overrides.
This knocks off a ~1% profile item on Speedometer 3.
The associated animations list might be modified on the time change
event. This means that we can't safely iterate over the hashmap during
this period.
This fixes a crash in:
- css/css-animations/CSSAnimation-effect.tentative.html
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
