Make body_owned_by return the body directly.

Almost all callers want this anyway, and now we can use it to also return fed bodies

compiler/rustc_passes/src/upvars.rs

@@ -16,17 +16,17 @@ pub fn provide(providers: &mut Providers) {
         }
 
         let local_def_id = def_id.expect_local();
-        let body = tcx.hir().body(tcx.hir().maybe_body_owned_by(local_def_id)?);
+        let body = tcx.hir().maybe_body_owned_by(local_def_id)?;
 
         let mut local_collector = LocalCollector::default();
-        local_collector.visit_body(body);
+        local_collector.visit_body(&body);
 
         let mut capture_collector = CaptureCollector {
             tcx,
             locals: &local_collector.locals,
             upvars: FxIndexMap::default(),
         };
-        capture_collector.visit_body(body);
+        capture_collector.visit_body(&body);
 
         if !capture_collector.upvars.is_empty() {
             Some(tcx.arena.alloc(capture_collector.upvars))