There is a NOTE in our implementation of these steps which states that
the effective overload set only contains overloads with the correct
number of arguments. While this is true, we should not skip the steps to
clamp the inspected argument count to that correct number. Otherwise, we
will dereference past the end of the overload set's type list as we
blindly iterate over the user-provided arguments.
Fixes#18670.
This class had slightly confusing semantics and the added weirdness
doesn't seem worth it just so we can say "." instead of "->" when
iterating over a vector of NNRPs.
This patch replaces NonnullRefPtrVector<T> with Vector<NNRP<T>>.
We now check if an argument value is a platform object that implements
the relevant IDL interface when resolving overloads.
This makes passing a Path2D object to CanvasRenderingContext2D.fill()
actually choose the Path2D overload. :^)
