Remove use of unstable box syntax.

http://www.robohornet.org gives a score of 101.36 on master,
and 102.68 with this PR. The latter is slightly better,
but probably within noise level.
So it looks like this PR does not affect DOM performance.

This is expected since `Box::new` is defined as:

```rust
impl<T> Box<T> {
    #[inline(always)]
    pub fn new(x: T) -> Box<T> {
        box x
    }
}
```

With inlining, it should compile to the same as box syntax.

1 files changed, 7 insertions, 4 deletions

diff --git a/components/script/dom/range.rs b/components/script/dom/range.rs
index b6a05b31881..00e2d23ce76 100644
--- a/components/script/dom/range.rs
+++ b/components/script/dom/range.rs
@@ -58,10 +58,13 @@ impl Range {
                start_container: &Node, start_offset: u32,
                end_container: &Node, end_offset: u32)
                -> DomRoot<Range> {
-        let range = reflect_dom_object(box Range::new_inherited(start_container, start_offset,
-                                                                end_container, end_offset),
-                                       document.window(),
-                                       RangeBinding::Wrap);
+        let range = reflect_dom_object(
+            Box::new(Range::new_inherited(
+                start_container, start_offset, end_container, end_offset
+            )),
+            document.window(),
+            RangeBinding::Wrap
+        );
         start_container.ranges().push(WeakRef::new(&range));
         if start_container != end_container {
             end_container.ranges().push(WeakRef::new(&range));