[base] Move hashmap allocator to a field

src/ast/ast.h

Index: src/ast/ast.h
diff --git a/src/ast/ast.h b/src/ast/ast.h
index 644dcb483b7d8e8f0ae18682cc3b894c2963a40e..c41da42e9ca092a35276ad432bd59c87031bcbae 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -134,14 +134,13 @@ typedef ZoneList<Handle<Object>> ZoneObjectList;
 class FeedbackVectorSlotCache {
  public:
   explicit FeedbackVectorSlotCache(Zone* zone)
-      : zone_(zone),
-        hash_map_(base::HashMap::PointersMatch,
+      : hash_map_(base::HashMap::PointersMatch,
                   ZoneHashMap::kDefaultHashMapCapacity,
                   ZoneAllocationPolicy(zone)) {}
 
   void Put(Variable* variable, FeedbackVectorSlot slot) {
-    ZoneHashMap::Entry* entry = hash_map_.LookupOrInsert(
-        variable, ComputePointerHash(variable), ZoneAllocationPolicy(zone_));
+    ZoneHashMap::Entry* entry =
+        hash_map_.LookupOrInsert(variable, ComputePointerHash(variable));
     entry->value = reinterpret_cast<void*>(slot.ToInt());
   }
 
@@ -150,7 +149,6 @@ class FeedbackVectorSlotCache {
   }
 
  private:
-  Zone* zone_;
   ZoneHashMap hash_map_;
 };
 
@@ -1477,7 +1475,7 @@ class AccessorTable
         zone_(zone) {}
 
   Iterator lookup(Literal* literal) {
-    Iterator it = find(literal, true, ZoneAllocationPolicy(zone_));
+    Iterator it = find(literal, true);
     if (it->second == NULL) it->second = new (zone_) ObjectLiteral::Accessors();
     return it;
   }