Convert remaining virtual methods to static methods dispatched
by kind. This makes ArrayData a non-virtual class, so shuffle
fields and adjust static_asserts.
Moves about half of ArrayData virtual methods to g_array_funcs as
static functions instead of virtual functions. This is mostly a
mechanical factor, except a handful of methods that are specialized
for Vector instead of generic HphpArray.
Introduces a new m_kind for vector-shaped HphpArray instances.
A vector has integer indexes in the range [0..size), and no
tombstones. Internally it does not store the integer keys or
hashtable, although this version still allocates space for it.
We'd like to start using ##mixed## instead of ##var## for attribute types to be consistent with Hack. As a followup to this (once released), we would codemod all ##var## to ##mixed##.
Edwin Smith