Expand newarray/expandarray optimization for unequal operands

This optimizes unbalanced multiple assignment cases such as:

```ruby
a.b, c.d = e, f, g
a.b, c.d, e.f = g, h
```

Previously, this would use:

```
newarray(3)
expandarray(2, 0)

newarray(2)
expandarray(3, 0)
```

These would both allocate arrays.  This switches to opt_reverse
with either pop or putnil:

```
pop
opt_reverse(2)

putnil
opt_reverse(3)
```

This avoids an unnecessary array allocation, and results in a 35-76%
performance increase in these types of unbalanced cases (tested with
benchmark/masgn.yml).

0 files changed, 0 insertions, 0 deletions