Split the `Edges` iterator.

The `Edges` iterator returns `OutlivesConstraint` elements, which are 72
bytes. This is big enough to affect performance. Return
`&OutlivesConstraint` would be better. However, each `Edges` iterator is
really one of two different iterators. The "from graph" case does a
graph traversal and could return `&OutlivesConstraint`. But the "from
static" case just does a `0..n` iteration and constructs a new
`OutlivesConstraint` from that, so it can't return a reference.

This commit splits `Edges into `EdgesFromGraph` and `EdgesFromStatic`,
which allows them to have different return types. This is a perf win for
the `wg-grammar` benchmark.

0 files changed, 0 insertions, 0 deletions