style: Stop allowing unused_unsafe.

components/style/lib.rs

@@ -26,15 +26,6 @@
 #![deny(warnings)]
 #![deny(missing_docs)]
 
-// FIXME(bholley): We need to blanket-allow unsafe code in order to make the
-// gecko atom!() macro work. When Rust 1.14 is released [1], we can uncomment
-// the commented-out attributes in regen_atoms.py and go back to denying unsafe
-// code by default.
-//
-// [1] https://github.com/rust-lang/rust/issues/15701#issuecomment-251900615
-//#![deny(unsafe_code)]
-#![allow(unused_unsafe)]
-
 #![recursion_limit = "500"]  // For define_css_keyword_enum! in -moz-appearance
 
 extern crate app_units;

components/style/rule_tree/mod.rs

@@ -590,9 +590,7 @@ impl PrevSiblingOrFreeCount {
     }
 
     unsafe fn as_free_count(&self) -> &AtomicUsize {
-        unsafe {
+        mem::transmute(&self.0)
-            mem::transmute(&self.0)
-        }
     }
 }