Assign less environments in StoreNamedField

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index e50be086bc7012619538c29f3d3539295cc1e809..59a833e2f4a1ea88b467f8864e3309726cc5afba 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -2294,10 +2294,11 @@ LInstruction* LChunkBuilder::DoStoreNamedField(HStoreNamedField* instr) {
       needs_write_barrier_for_map) ? TempRegister() : NULL;
 
   LStoreNamedField* result = new(zone()) LStoreNamedField(obj, val, temp);
-  if ((FLAG_track_fields && instr->field_representation().IsSmi()) ||
-      (FLAG_track_heap_object_fields &&
-       instr->field_representation().IsHeapObject())) {
-    return AssignEnvironment(result);
+  if (FLAG_track_heap_object_fields &&
+      instr->field_representation().IsHeapObject()) {
+    if (!instr->value()->type().IsHeapObject()) {
+      return AssignEnvironment(result);
+    }
   }
   return result;
 }