Use Layout::new consistently in DroplessArena::alloc.

Author: nnethercote

compiler/rustc_arena/src/lib.rs

@@ -501,12 +501,13 @@ impl DroplessArena {
         assert!(!mem::needs_drop::<T>());
         assert!(mem::size_of::<T>() != 0);
 
-        let mem = if let Some(a) = self.alloc_raw_without_grow(Layout::for_value::<T>(&object)) {
+        let layout = Layout::new::<T>();
+        let mem = if let Some(a) = self.alloc_raw_without_grow(layout) {
             a
         } else {
             // No free space left. Allocate a new chunk to satisfy the request.
             // On failure the grow will panic or abort.
-            self.grow_and_alloc_raw(Layout::new::<T>())
+            self.grow_and_alloc_raw(layout)
         } as *mut T;
 
         unsafe {