Bug 1280578 added some wrapping for the Win32 Heap* functions, mainly
for the rust static libraries that use them. Because pointer ownership
might cross the C++/Rust boundary, and because about:memory uses
malloc_usable_size/msize, we need both C++ and Rust to still use the
same heap on builds where our allocator is not enabled.
The Win32 has non-malloc based heap allocation functions. They are not
widely used in the Gecko code base, but there are a few places that do
use them. They could be replaced with uses of malloc/free/realloc or
new/delete, but there is now an entirely separate problem that
requires wrapping those functions: the Rust static libraries are using
those functions to allocate memory.
