Avoid closures in the default <Zip as ZipImpl>::next

Author: cuviper

src/libcore/iter/adapters/zip.rs

@@ -94,11 +94,9 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
 
     #[inline]
     default fn next(&mut self) -> Option<(A::Item, B::Item)> {
-        self.a.next().and_then(|x| {
-            self.b.next().and_then(|y| {
-                Some((x, y))
-            })
-        })
+        let x = self.a.next()?;
+        let y = self.b.next()?;
+        Some((x, y))
     }
 
     #[inline]