Avoid SmallSet in Proxy/HostObject cases

Summary:
These were using `SmallSet` when the keys were just integers,
but `SmallSet` is backed by `std::set` instead of `DenseSet`.

Switch to DenseSet and keep determinism by using `SmallSetVector` if
necessary.

Reviewed By: tmikov

Differential Revision: D67548060

fbshipit-source-id: f5666fa8ab7cb250bbb151652784bfc05b49933e

lib/VM/JSObject.cpp

@@ -17,7 +17,7 @@
 #include "hermes/VM/Operations.h"
 #include "hermes/VM/PropertyAccessor.h"
 
-#include "llvh/ADT/SmallSet.h"
+#include "llvh/ADT/DenseSet.h"
 
 namespace hermes {
 namespace vm {
@@ -396,7 +396,7 @@ CallResult<Handle<JSArray>> JSObject::getOwnPropertyKeys(
   size_t hostObjectSymbolCount = 0;
 
   // If current object is a host object we need to deduplicate its properties
-  llvh::SmallSet<SymbolID::RawType, 16> dedupSet;
+  llvh::SmallDenseSet<SymbolID::RawType, 16> dedupSet;
 
   // Output index.
   uint32_t index = 0;

lib/VM/JSProxy.cpp

@@ -14,7 +14,7 @@
 #include "hermes/VM/JSMapImpl.h"
 #include "hermes/VM/PropertyAccessor.h"
 
-#include "llvh/ADT/SmallSet.h"
+#include "llvh/ADT/SetVector.h"
 
 namespace hermes {
 namespace vm {
@@ -1455,7 +1455,7 @@ CallResult<PseudoHandle<JSArray>> JSProxy::ownPropertyKeys(
   // 13. Assert: targetKeys contains no duplicate entries.
   // 14. Let targetConfigurableKeys be a new empty List.
   // 15. Let targetNonconfigurableKeys be a new empty List.
-  llvh::SmallSet<uint32_t, 8> nonConfigurable;
+  llvh::SmallSetVector<uint32_t, 8> nonConfigurable;
   MutableHandle<SymbolID> tmpPropNameStorage{runtime};
   // 16. For each element key of targetKeys, do
   GCScopeMarkerRAII marker{runtime};