No-op refactor: root_flow param for perform_post_style_recalc_layout_passes

This whole method was a large `if let` block:

```rust
if let Some(mut root_flow) = self.root_flow.clone() {
   // ...
}
```

Move that `if let` to callers to make it clear that the method
doesn’t need to be called when `self.root_flow` is `None`.

By itself, this commit doesn’t change anything.
But it enables the next one.

0 files changed, 0 insertions, 0 deletions