* simple failing jit test case with Tensor.empty
* this used to exist in ops.py...
* Revert "removed if self.buffer.is_allocated() in realized (#14836)"
This reverts commit 72cf603805.
undo the view and make it a mask, this fuses the setitem with any pending compute too.
one behavior change is that for target not backed by a buffer (const and arange), rangeify makes output contiguous under the hood.
this is stricter better than raise and ask user to call contiguous, as that would no longer be fuse-able.
