perf(manger): remove useless tmp_bindings (#8735)

We don't need `tmp_bindings` to store sorted bindings as `sorted_unstable` can return an iterator and nowhere else needs to use `tmp_bindings`.

crates/oxc_mangler/src/lib.rs

@@ -185,7 +185,6 @@ impl Mangler {
         // Stores the lived scope ids for each slot. Keyed by slot number.
         let mut slot_liveness: std::vec::Vec<FixedBitSet> = vec![];
 
-        let mut tmp_bindings = std::vec::Vec::with_capacity(100);
         let mut reusable_slots = std::vec::Vec::new();
         // Walk down the scope tree and assign a slot number for each symbol.
         // It is possible to do this in a loop over the symbol list,
@@ -218,12 +217,8 @@ impl Mangler {
             }
 
             // Sort `bindings` in declaration order.
-            tmp_bindings.clear();
-            tmp_bindings.extend(bindings.values().copied());
-            tmp_bindings.sort_unstable();
-            for (&symbol_id, assigned_slot) in
-                tmp_bindings.iter().zip(reusable_slots.iter().copied())
-            {
+            let sorted_bindings = bindings.values().copied().sorted_unstable();
+            for (symbol_id, assigned_slot) in sorted_bindings.zip(reusable_slots.iter().copied()) {
                 slots[symbol_id.index()] = assigned_slot;
 
                 // If the symbol is declared by `var`, then it can be hoisted to