Work around rust-lang/rust#16643

Author: kmcallister

src/tree_builder/rules.rs

@@ -373,15 +373,25 @@ impl<'sink, Handle: Clone, Sink: TreeSink<Handle>>
                     self.frameset_ok = false;
 
                     let mut to_close = None;
-                    for node in self.open_elems.iter().rev() {
-                        let nsname = self.sink.elem_name(node.clone());
-                        if can_close(nsname.clone()) {
-                            let (_, name) = nsname;
-                            to_close = Some(name);
-                            break;
-                        }
-                        if extra_special(nsname.clone()) {
-                            break;
+                    // FIXME: using a 'for' loop here ICEs the compiler
+                    // (rust-lang/rust#16643)
+                    {
+                        let mut iter = self.open_elems.iter().rev();
+                        loop {
+                            match iter.next() {
+                                None => break,
+                                Some(node) => {
+                                    let nsname = self.sink.elem_name(node.clone());
+                                    if can_close(nsname.clone()) {
+                                        let (_, name) = nsname;
+                                        to_close = Some(name);
+                                        break;
+                                    }
+                                    if extra_special(nsname.clone()) {
+                                        break;
+                                    }
+                                }
+                            }
                         }
                     }